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Skinny peanut butter brownies are made with a lightened up brownie mix, and topped with a peanut butter and marshmallow creme topping.

I sometimes refer to this recipe as two ingredient brownies. They start out with a simple boxed sugar-free brownie mix, but rather than adding eggs and oil, I add Diet Coke. It’s crazy to think that adding just cola to a brownie mixture can make brownies, right?
The batter won’t be quite as thick as making the brownies according to the box, but it bakes into fluffy, delicious brownies.
I add some peanut butter powder into marshmallow creme, then use it to top the brownies in a nice, thin layer. It’s the perfect pop of creme and peanut butter!

Why you’ll love this recipe
- Brownies with less calories
- A guiltless way to indulge in a sweet treat
- Made with a boxed mix for less fuss
- Topped with a delicious peanut butter marshmallow creme

Ingredients
What you’ll need to make this recipe.

How to make this recipe
1 – Preheat the oven to 350 degrees. Spray an 8×8-inch baking dish with nonstick cooking spray.
2 – Add the brownie mix and Diet Coke to a medium sized mixing bowl and mix together with a wooden spoon. Be careful to not over mix. Brownie mix will be runny.
3 – Pour the brownie batter into the prepared baking dish. Bake for 35-40 minutes, until brownies are cooked through. Use a toothpick to check center. Allow brownies to cool completely.
4 – In a small bowl, add the peanut butter powder and water and mix together. Add the marshmallow creme and together mix again.
5 – Spread mixture evenly over brownies. Enjoy!

How do I store my leftover brownies?
Place brownies in an airtight container and store on the countertop for 3-4 days.
Calories per serving (1/12 serving): 127
Skinny Peanut Butter Brownies

Skinny peanut butter brownies are made with a lightened up brownie mix, and topped with a peanut butter and marshmallow creme topping. Perfect for a guiltless treat.
Ingredients
- 12.35 ounce 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 8x8-inch baking dish with nonstick cooking spray.
- Add the brownie mix and Diet Coke to a medium sized mixing bowl and mix together with a wooden spoon. Be careful to not over mix. Brownie mix will be runny.
- Pour the brownie batter into the prepared baking dish. Bake for 35-40 minutes, until brownies are cooked through. Use a toothpick to check center. Allow brownies to cool completely.
- In a small bowl, add the peanut butter powder and water and mix together. Add the marshmallow creme and together mix again.
- Spread mixture evenly over brownies. Enjoy!
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Wilton Perfect Results Premium Non-Stick 8-Inch Square Cake Pans, Set of 2
Nutrition Information:
Yield:
12Amount Per Serving: Calories: 127Total Fat: 2gSaturated Fat: 0gTrans Fat: 0gUnsaturated Fat: 0gCholesterol: 0mgSodium: 100mgCarbohydrates: 32gFiber: 4gSugar: 6gProtein: 1g
Nutritional information is only an estimate. The accuracy of the nutritional information for any recipe on this site is not guaranteed.
Other recipes you’ll love
Whipped Topping Ice Cream Sandwiches
Lemon Cake With Pineapple Filling
Chocolate Cupcakes With Whipped Chocolate Frosting
I’d love to hear your thoughts. Comment below or tag me on Instagram. And don’t forget to Pin it for later!


Cool Cook
Sunday 19th of July 2020
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.
simplylowcal
Monday 20th of July 2020
I've never tried using seltzer water. Let me know how it goes. :)
Gloria
Tuesday 7th of July 2020
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.
simplylowcal
Wednesday 8th of July 2020
Thanks, Gloria. I hope you enjoy them. :)
Sharon
Tuesday 7th of July 2020
I've never seen diet coke in brownies!! I have a friend who LIVES for diet coke. She's going to love this recipe. :)
simplylowcal
Wednesday 8th of July 2020
That's great, Sharon! I hope she enjoys it. :)
Lizet Bowen
Tuesday 7th of July 2020
I think everybody needs a recipe like this one. Skinny chocolate peanut butter brownies! to die for. :)
simplylowcal
Wednesday 8th of July 2020
Thanks, Lizet! :)
Kushigalu
Monday 6th of July 2020
These brownies look fantastic. One of the best combination ever. Thanks for sharing
simplylowcal
Monday 6th of July 2020
Thanks, Kushigalu. :)