Cannot stop making this!! Peanut Butter Mississippi Mud Brownies

How sick of peanut butter are you all? Because heaven knows I post enough of it. I just cannot help it! It’s so darn creamy and delightful! This particular recipe for Peanut Butter Mississippi Mud Blondies has actually been a 3 year long process.

Cannot stop making this!! Peanut Butter Mississippi Mud Brownies

It shouldn’t be this hard but I kept testing blondie recipes and peanut butter blondies and they just weren’t perfect.

Cannot stop making this!! Peanut Butter Mississippi Mud Brownies

I like my brownies and bars to be chewy and not cake like so there was that issue right there, but then I also found many recipes ended up really dry or had too much texture with the addition of oats or nuts. No, I wanted a chewy, gooey, melt in your mouth bar that made your eyes roll back in your head. And I mean that in a good way, not a “I just died these were so bad”.

Cannot stop making this!! Peanut Butter Mississippi Mud Brownies

I found that softened, unsalted butter was the key unlike many blondies that called for melted butter. Also beating the butter and sugar together for a full minute helped the batter lighten up just enough that they weren’t cake like but they were chewy and gooey. I experimented with white, brown, dark brown and combinations but in the end pure brown sugar ended up being best. And of course peanut butter in the batter as opposed to just peanut butter chips. This really brought on the nutty flavor. It’s like a blondie and lunch lady peanut butter bar got married. Love is totally in the air.

Cannot stop making this!! Peanut Butter Mississippi Mud Brownies

The marshmallows, well mini worked best as the large mallows ended up too puffy and aired out in the middles thus reducing the gooey factor. And marshmallow creme was just too sweet. Don’t ask me why, it’s just how I feel. The chocolate frosting was a back and forth ordeal. Originally I wanted to use Mom’s Texas Sheet Cake cooked chocolate frosting, but it didn’t give enough chocolate flavor to balance everything out and a ganache just totally ran and solidified so that was out. I ended up with a simple chocolate frosting and I’m in pure heaven. Next up, a cookie version so stay tuned!

Is Confectioners Sugar The Same As Powdered Sugar?

They are the same thing. Sometimes it’s also called icing sugar.

What are Blondies?

Blondies are a rich, sweet cookie bar.

They resemble chocolate brownies, but the chocolate is replaced by vanilla, and they contain brown sugar.

Can You Substitute Almond Butter for Peanut Butter in Recipes?

Almond butter has the same thick, creamy consistency as peanut butter.

Almond butter also has a good “nut” flavor.

You can substitute almond butter for peanut butter in recipes.

Peanut Butter Mississippi Mud Blondies

Peanut Butter Mississippi Mud Blondies

4.58 from 7 votes
Servings: 9
Prep Time: 15 minutes
Cook Time: 28 minutes
Total Time: 43 minutes


  • 1/4 Cup Butter, softened
  • 1 Cup Brown Sugar
  • 1/4 Cup Peanut Butter
  • 1 Large Egg
  • 2 teaspoons Vanilla
  • 1 Cup Flour
  • 1/2 teaspoon Baking Powder
  • 1/4 teaspoon Salt
  • 1/2 Cup Peanut Butter Chips
  • 2 Cups Mini Marshmallows


  • 1/4 Cup Butter, softened
  • 3 Tablespoons Cocoa Powder
  • 2 Cups Powdered Sugar
  • 1/4 Cup Heavy Cream, plus 2 Tablespoons
  • 1/4 teaspoon Vanilla


  • Preheat the oven to 350 degrees and line an 8x8" baking pan with parchment paper sprayed lightly with nonstick spray.
  • In the bowl of a standing mixer, cream together the butter and brown sugar for 1 minute.
    1/4 Cup Butter, 1 Cup Brown Sugar
  • Add the peanut butter and mix for 30 seconds.
    1/4 Cup Peanut Butter
  • Add the egg and vanilla and beat until smooth, scraping down the sides.
    1 Large Egg, 2 teaspoons Vanilla
  • In a medium bowl, whisk together the flour, baking powder and salt.
    1 Cup Flour, 1/2 teaspoon Baking Powder, 1/4 teaspoon Salt
  • Add to the wet ingredients and mix until combined.
  • Fold in the peanut butter chips.
    1/2 Cup Peanut Butter Chips
  • Press the dough into the pan and bake for 25-28 minutes, remove from the oven and top with marshmallows then bake an additional 1-2 minutes.
    2 Cups Mini Marshmallows
  • Remove the pan from the oven and allow to cool for 10 minutes then add dollops of frosting and allow to sit another few minutes to soften the frosting.
  • Spread gently with a spatula and serve.

For the frosting

  • In a large bowl, using a hand mixer, beat the butter and cocoa.
    1/4 Cup Butter, 3 Tablespoons Cocoa Powder
  • Add the powdered sugar, cream and vanilla and beat until smooth.
    2 Cups Powdered Sugar, 1/4 Cup Heavy Cream, 1/4 teaspoon Vanilla


can be frozen for 2-3 months


Serving: 1gCalories: 519kcalCarbohydrates: 68.4gProtein: 7.8gCholesterol: 61.4mgFiber: 2.1gSugar: 50.9g
Author: Sweet Basil
Course: 100 Best Brownies and Bars Recipes

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