• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
Simply Low Cal
  • Low Calorie Recipes
    • Air Fryer
    • Appetizers
    • Breakfast
    • Dessert
    • Main Dish
    • Dips, Dressings & Sauces
    • Drinks
    • Instant Pot
    • Recipe Roundups & Downloads
    • Salads
    • Side Dish
    • Slow Cooker
    • Soup
    • Snack
    • Email
    • Facebook
    • Instagram
    • Pinterest
    • RSS
    • Twitter
    • YouTube
menu icon
go to homepage
  • Recipes +
  • Easy Main Dishes
  • About
  • Contact
    • Facebook
    • Instagram
    • Pinterest
  • subscribe
    search icon
    Homepage link
    • Recipes +
    • Easy Main Dishes
    • About
    • Contact
    • Facebook
    • Instagram
    • Pinterest
  • ×
    Home » Dessert

    Marshmallow Fluff Brownies

    Published: July 6, 2020 · Modified: November 26, 2024 by Kate · This post may contain affiliate links. As an Amazon associate, I earn from qualifying purchases.

    192 shares
    • Share
    • Yum
    • Email
    Jump to Recipe
    skinny peanut butter brownies pin.

    These Marshmallow Fluff Brownies are made with sugar free brownie mix, Diet Coke, and peanut butter powder. They're lower in calories and sugar than traditional brownies. Plus, the addition of marshmallow creme on top adds a fluffy and delicious twist.

    Three brownies stacked on a plate.
    Jump to:
    • Why You'll Love This Recipe
    • Ingredients You'll Need
    • Step-By-Step Instructions
    • Expert Tips
    • Variations
    • Storing & Freezing
    • Recipe FAQ's
    • More Chocolate Dessert Recipes You'll Love
    • Marshmallow Fluff Brownies
    • #respond

    Check out my Gluten Free Fudge Brownies and my Chocolate Chip Cookie Bars for more delicious chocolate recipes!

    Marshmallow fluff brownies are a delicious and healthier twist on traditional brownies. They are made with Pillsbury sugar-free brownie mix, which is lower in calories and sugar, and Diet Coke, which replaces the need for eggs and oil.

    Peanut butter powder is added to give the brownies a nutty flavor without the added fat and calories of regular peanut butter. Marshmallow creme is added on top for a fluffy and decadent finish!

    More lighter and healthier dessert recipes to try: Healthier Tiramisu

    Why You'll Love This Recipe

    • This recipe uses sugar free brownie mix and Diet Coke, which makes it a lower calorie and lower sugar option compared to traditional brownies.
    • The addition of peanut butter powder gives these brownies a delicious nutty flavor without the added fat and calories of regular peanut butter.
    • This recipe is quick and easy to make, using only a few ingredients and minimal prep time.
    • The marshmallow creme adds a fluffy and decadent finish to the brownies, making them a delicious and satisfying treat.

    Ingredients You'll Need

    Labeled ingredients for the brownies.
    • Sugar Free Brownie Mix: Pillsbury sugar free brownie mix is a great option for those looking to reduce the amount of sugar and calories in their brownies. It contains all the necessary dry ingredients to make delicious brownies, while keeping the sugar and calorie content low.
    • Diet Coke: Used as a replacement for eggs and oil in this recipe, which helps to reduce the calorie and fat content of the brownies.
    • Water: Used to help mix all the ingredients together for the topping.
    • Peanut Butter Powder: Used in this recipe to give the brownies a nutty flavor without adding excess fat and calories.
    • Marshmallow Creme: A soft, spreadable mixture of marshmallow and corn syrup. It is used in this recipe to add a fluffy and decadent finish to the brownies.

    Step-By-Step Instructions

    Steps to make the brownies.
    Steps to make the marshmallow fluff.

    Step 1: Preheat the oven to 350 °F Spray an 8-inch square baking dish with nonstick cooking spray.

    Step 2: In a mixing bowl, combine the Pillsbury sugar-free brownie mix and Diet Coke together with a wooden spoon. Brownie mix will be runny. 

    Step 3: Pour the batter into the prepared baking dish and bake for 35-40 minutes, or until a toothpick inserted in the center comes out clean.

    Step 4: Remove the brownies from the oven and let them cool completely in the baking dish.

    Step 5: In a small bowl, combine the peanut butter powder and water. Add the marshmallow creme and mix again. 

    Step 6: Once the brownies have cooled, spread the marshmallow creme mixture over the top of the brownies.

    NOTE: You can print the FULL recipe with all ingredients & detailed instructions below!

    Piece of brownie on a fork.

    Expert Tips

    • When mixing the ingredients together, be careful not to overmix the batter. Overmixing can cause the brownies to become tough and chewy.
    • Allow the brownies to cool completely before adding the marshmallow creme on top. This will prevent the creme from melting and becoming runny.
    • You can customize the recipe by using different flavors of sugar-free brownie mix, such as chocolate fudge or dark chocolate, and by adding other ingredients like chopped nuts or chocolate chips.

    Variations

    • Add chocolate chips: For a little extra sweetness and texture, you can add sugar-free chocolate chips to the batter before baking.
    • Use different nut butters: Instead of peanut butter powder, you can use almond butter powder or another type of nut butter powder for a different flavor.
    • Use different sweeteners: Instead of using marshmallow creme, you can use a sugar-free frosting or whipped cream.
    • Add fruit: For a healthier twist, you can add chopped strawberries or raspberries on top of the brownies instead of the marshmallow creme.

    Storing & Freezing

    Storing: To store skinny peanut butter brownies, allow them to cool completely and then place them in an airtight container. You can keep them at room temperature for up to 3 days or in the refrigerator for up to 1 week.

    Freezing: If you want to freeze the brownies, wrap them tightly in plastic wrap and then place them in an airtight container or freezer bag. They will last in the freezer for up to 3 months.

    Reheating: Remove them from the freezer and let them come to room temperature. You can also warm them up in the microwave or oven if you prefer to eat them warm. Just be sure to remove the plastic wrap before reheating.

    Recipe FAQ's

    Can I use regular brownie mix instead of sugar free brownie mix?

    Yes, you can use regular brownie mix if you prefer. However, keep in mind that it will increase the calorie and sugar content of the brownies.

    Can I use regular peanut butter instead of peanut butter powder?

    Yes, you can use regular peanut butter, but keep in mind that it will increase the fat and calorie content of the brownies.

    Can I use a different type of soda instead of Diet Coke?

    Yes, you can use any type of soda, but keep in mind that it may change the flavor of the brownies.

    Can I skip the marshmallow creme on top?

    Yes, you can skip the marshmallow creme if you prefer. You can also use a different type of frosting or topping if you like.

    More Chocolate Dessert Recipes You'll Love

    • Thumbnail of homemade chocolate pudding without cornstarch.
      Homemade Chocolate Pudding Without Cornstarch
    • Thumbnail of low calorie chocolate cupcakes.
      Low Calorie Chocolate Cupcakes
    • Thumbnail of cool whip peanut butter treats.
      Cool Whip Peanut Butter Cups
    • Thumbnail of sugar free chocolate sorbet.
      Sugar Free Chocolate Sorbet

    If you love this recipe, please leave a comment with a five-star rating — or simply hit the five-star button in the recipe card. Don't forget to signup for my newsletter!

    Thumbnail of marshmallow fluff brownies.

    Marshmallow Fluff Brownies

    4.95 from 17 votes
    By Kate
    These marshmallow fluff brownies are made with sugar free brownie mix, Diet Coke, and peanut butter powder. They're lower in calories and sugar than traditional brownies. Plus, the addition of marshmallow creme on top adds a fluffy and delicious twist.
    Pin Recipe Print Recipe Save RecipeSaved!
    Prep 15 minutes mins
    Cook 35 minutes mins
    Total 50 minutes mins
    Servings 12 Servings
    Calories 127kcal
    Prevent your screen from going dark

    Special Equipment

    • Utensil Set
    • Measuring Spoons and Cups
    • Stainless Steel Mixing Bowls
    • 8-Inch Square Cake Pans

    Ingredients
     
     

    • 12.35 ounces Pillbury sugar free brownie mix
    • 12 ounces Diet Coke
    • 2 tablespoons peanut butter powder
    • 1 tablespoon water
    • 4 ounces marshmallow creme

    Instructions
     

    • Preheat the oven to 350°. Spray an 8-inch square baking dish with nonstick cooking spray.
    • In a mixing bowl, combine the sugar-free brownie mix and Diet Coke together with a wooden spoon. Brownie mix will be runny. 
    • Pour the batter into the prepared baking dish and bake for 35-40 minutes, or until a toothpick inserted in the center comes out clean.
    • Remove the brownies from the oven and let them cool completely in the baking dish.
    • In a small bowl, combine the peanut butter powder and water. Add the marshmallow creme and mix again. 
    • Once the brownies have cooled, spread the marshmallow creme mixture over the top of the brownies.

    Notes

    • When mixing the ingredients together, be careful not to overmix the batter. Overmixing can cause the brownies to become tough and chewy.
    • Allow the brownies to cool completely before adding the marshmallow creme on top. This will prevent the creme from melting and becoming runny.
    • You can customize the recipe by using different flavors of sugar-free brownie mix, such as chocolate fudge or dark chocolate, and by adding other ingredients like chopped nuts or chocolate chips.
    • Storing: Allow the brownies to cool completely and then place them in an airtight container. You can keep them at room temperature for up to 3 days or in the refrigerator for up to 1 week.
    • Freezing: If you want to freeze the brownies, wrap them tightly in plastic wrap and then place them in an airtight container or freezer bag. They will last in the freezer for up to 3 months.
    • Reheating: Remove them from the freezer and let them come to room temperature. You can also warm them up in the microwave or oven if you prefer to eat them warm. Just be sure to remove the plastic wrap before reheating.

    Nutrition

    Calories: 127kcalCarbohydrates: 32gProtein: 1gFat: 2gSodium: 100mgFiber: 4gSugar: 6g

    All nutritional information is based on third-party calculations and should be considered estimates. Actual nutritional content will vary with brands used, measuring methods, portion sizes and more.

    Tried this recipe?Give it a star rating and leave a comment below!
    Signature.

    More Dessert

    • Slice of low calorie carrot cake
      Low Calorie Carrot Cake
    • Thumbnail of low calorie lemon cake.
      Low Calorie Lemon Cake
    • Thumbnail of low calorie mug cake.
      Low Calorie Mug Cake
    • Thumbnail of protein banana bread recipe.
      Protein Banana Bread Recipe
    192 shares
    • Share
    • Yum
    • Email

    Reader Interactions

    Comments

    1. Cool Cook

      July 19, 2020 at 3:04 pm

      I'm not sure the sweetener in diet coke is heat-stable. So I'm leery of doing that. I might try this with unsweetened Seltzer water, though.

      Reply
      • simplylowcal

        July 20, 2020 at 8:04 pm

        I've never tried using seltzer water. Let me know how it goes. 🙂

        Reply
    2. Gloria

      July 07, 2020 at 6:50 pm

      I love the peanut butter chocolate combo. A healthier version of the classic treat is perfect. Now I can enjoy it when I crave something sweet.

      Reply
    3. Sharon

      July 07, 2020 at 5:15 pm

      I've never seen diet coke in brownies!! I have a friend who LIVES for diet coke. She's going to love this recipe. 🙂

      Reply
    4. Lizet Bowen

      July 07, 2020 at 3:56 pm

      I think everybody needs a recipe like this one. Skinny chocolate peanut butter brownies! to die for. 🙂

      Reply
    5. Kushigalu

      July 06, 2020 at 4:19 pm

      These brownies look fantastic. One of the best combination ever. Thanks for sharing

      Reply
    6. Angela

      July 06, 2020 at 4:17 pm

      The addition of the diet coke is such a interesting ingredient. I had to try it for myself. It did bake up nice and fluffy.

      Reply
    7. Jenn

      July 06, 2020 at 3:54 pm

      I love love love that I can indulge in something sweet and not have to worry about the calories as much! Stellar idea - thank you! Making this weekend!

      Reply
    4.95 from 17 votes (11 ratings without comment)

    Leave a Reply Cancel reply

    Your email address will not be published. Required fields are marked *

    Recipe Rating




    Primary Sidebar

    skinny peanut butter brownies pin.
    Headshot of Kate the blog owner

    Hi and welcome! Simply Low Cal is the blog about DELICIOUS low calorie recipes for breakfast, lunch, dinner, dessert, and snacks that anyone can make. You will find plenty of healthy recipes for anyone. About Me

    POPULAR RECIPES

    • Thumbnail of low calorie banana bread.
      Low Calorie Banana Bread
    • Thumbnail of low calorie chicken noodle soup.
      Low Calorie Chicken Noodle Soup
    • Thumbnail of healthy snow cone syrup.
      Healthy Snow Cone Syrup
    • Thumbnail of 100 calorie blueberry muffins.
      100 Calorie Blueberry Muffins
    • Thumbnail of low calorie protein shake.
      Low Calorie Protein Shake
    • Thumbnail of PBfit soft gluten free cookies.
      PBfit Soft Gluten Free Peanut Butter Cookies

    THE BEST OF WINTER

    • Thumbnail of low calorie hot chocolate.
      Low Calorie Instant Pot Hot Chocolate
    • Thumbnail of low calorie pecan pie.
      Low Calorie Pecan Pie
    • Thumbnail of low calorie gingerbread latte.
      Low Calorie Gingerbread Latte
    • Thumbnail of low calorie mashed cauliflower.
      Low Calorie Mashed Cauliflower
    • Thumbnail of low calorie snickerdoodle latte.
      Low Calorie Snickerdoodle Latte
    • Thumbnail of low calorie broccoli cheddar soup.
      Low Calorie Broccoli Cheddar Soup

    FEATURED IN

    as seen in.

    Footer

    skinny peanut butter brownies pin.

    ↑ back to top

    Featured In

    as seen in banner.

    About

    • Privacy Policy
    • Work With Me
    • Accessibility

    Newsletter

    • Sign Up! For emails and updates

    Contact

    • [email protected]

    AS AN AMAZON ASSOCIATE I EARN FROM QUALIFYING PURCHASES.

    © 2025 SIMPLY LOW CAL | MAMA IS WORKING LLC

    Rate This Recipe

    Your vote:




    A rating is required
    A name is required
    An email is required

    Recipe Ratings without Comment

    Something went wrong. Please try again.