Peanut Butter Stuffed Brownies are a quick and easy way to transform a boring box of brownie mix into a deliciously decadent dessert.

This simple shortcut recipe combines basic ingredients without using a mixer, and bakes a batch of brownies with a pretty pattern by swirling peanut butter into a pan with chocolate batter.

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Best Peanut Butter Stuffed Brownies

This Peanut Butter Brownies recipe is an easy way to turn regular brownies into the ultimate indulgent treat, simply by dropping spoonfuls of a chocolate batter and a homemade peanut butter mixture into a pan, and swirling them together to make a marbled pattern before baking.

These tasty treats are chewy around the edges and fudgy in the middle, with extra melted chocolate chips mixed in.

If you too are a fan of the chocolate peanut butter flavor combination, check out my Buckeyes, Peanut Butter Pretzel Bites, Buckeye Fudge, and so many more!

Why We Love This Peanut Butter Stuffed Brownies Recipe

  • Quick and easy to make using a shortcut.
  • Only uses 6 simple ingredients plus what’s called for on the box.
  • The slight saltiness of the peanut butter adds the perfect balance to the sweet chocolate.
  • Great way to get kids in the kitchen and fun for them to dump and stir.
  • Fudgy brownies swirled with smooth peanut butter makes a rich, decadent dessert.
  • Perfect for party platters, an after school snack, or a sweet treat after supper.
bitten peanut butter stuffed brownies

Ingredients

  • Creamy peanut butter
  • Salted butter: If you decide to use unsalted butter instead, add an extra pinch of salt for more flavor.
  • Half and half: You could switch this out for heavy cream for a slightly thicker peanut butter mixture.
  • Powdered sugar, sifted
  • Box brownie mix: Use either regular or gluten-free brownie mix. You’ll need the ingredients called for on the brownie mix package as well.
  • Semi-sweet chocolate chips

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Substitutions and Additions

  • Beyond Peanut Butter: You can replace the peanut butter with other similarly processed nut butters, such as Barney Butter almond butter, Sunbutter, or processed cashew butter. Make sure you do not use a “natural style” peanut butter alternative because the oils will separate from the other ingredients during baking.
  • More Mix-Ins: The brownie recipe calls for optional chocolate chips in the batter, but you could swap in things like chopped nuts, peanut butter chips, Reese’s Pieces, or chopped peanut butter cups.
  • Choose Your Chip: Some brownie mixes already include chocolate chips. You can omit these if that is the case, or add less. You can also use dark chocolate chips, milk chocolate chips, peanut butter chips, or butterscotch chips instead. 
  • 9×13 baking dish
  • Mixing bowl and tools
  • Microwave safe mixing bowl
  • Measuring tools
  • Parchment paper
  • Cooking spray

How to Make Peanut Butter Stuffed Brownies

These Peanut Butter Stuffed Brownies are quick and easy to make with a simple shortcut to save you time in the kitchen. By combining a homemade peanut butter mixture with the chocolate brownie batter, you can create a pretty-patterned dessert that’s fuss-free and no-fail. 

  1. Make The Peanut Butter Mixture: Microwave the peanut butter and butter for 30-45 seconds or until the butter has melted and stir to combine. Pour in the half and half and stir. Gradually stir in the powdered sugar until completely incorporated.
    Pro Tip: The mixture should end up with a consistency similar to a soft cookie dough.
  2. Prepare The Brownie Batter: Prepare the brownie batter according to the box instructions. Fold in the chocolate chips and stir to combine. 
  3. Prepare The Pan: Evenly drop alternating spoonfuls of brownie batter and the peanut butter mixture into the pan until you have covered the entire bottom. Use a spoon or knife to combine the mixtures together to form a marbled pattern.
    Pro Tip: Do not overmix or you will lose the marbling effect. 
  4. Bake The Brownies: Bake at 350 degrees Fahrenheit for 35-40 minutes or until the brownie edges are baked and the center has set. 
  5. Serve: Cool completely for about 30 minutes to 1 hour before cutting and serving. Enjoy!
collage process peanut butter stuffed brownies

Tips

  • Line the pan with parchment paper for easy removal. Once the brownies have cooled, you can lift the whole batch right out of the pan using the paper. 
  • Use a commercial brand of peanut butter that is fully combined/emulsified. I do not recommend using a “natural” peanut butter because the oil tends to separate. 
  • Make sure your peanut butter is creamy because crunchy peanut butter is difficult to work with.
  • When swirling the peanut butter into the brownie batter, less is more. If you swirl too much, you will mix the peanut butter into the batter.
peanut butter stuffed brownies in a baking pan

Storage Tips

  • To Store: Make sure to cover or wrap your Peanut Butter Brownies for maximum freshness and storage. Individually wrapped brownies will last for 1-2 days at room temperature or up to 4 days in the refrigerator.
  • To Freeze: You can freeze these brownies for 1-2 months and thaw overnight in the refrigerator before serving. 
peanut butter stuffed brownies squares

Frequently Asked Questions

How will I know when my brownies are done baking?

Do not overbake your brownies! If you insert a toothpick into the center it should have moist, fudgy crumbs on it, but no batter. As soon as that happens, pull them out. Since all ovens bake differently, set your timer for earlier than the recipe calls for and keep checking them until they’re done.

What if I don’t have parchment paper?

Due to the nature of the ingredients, these brownies tend to stick to the pan, which is why I recommend parchment paper with cooking spray. If you don’t have any, be liberal when spraying your cooking spray on the pan when preparing it.

Can I add more peanut butter flavor to these brownies?

For more peanut butter flavor, use Reese’s Peanut Butter Cups or Reese’s Pieces in the brownies instead of the chocolate chips.
Chop the cups up roughly before you add them to the brownie mix. You can also sprinkle some on top after the brownies come out of the oven if you would like! You can also drizzle the brownies with melted peanut butter and/or a sprinkle of sea salt when they come out of the oven. 

peanut butter brownie bars

Other Easy Peanut Butter and Chocolate Recipes

5 from 2 votes
peanut butter stuffed brownies featured image

Peanut Butter Brownies

Serves — 12
Peanut Butter Brownies combine 2 classic flavors into 1 deliciously decadent dessert. This quick and easy recipe makes a marbled-looking sweet treat in under 50 minutes from start to finish.
Prep Time 25 minutes
Cook Time 25 minutes
Total Time 50 minutes

Ingredients
  

Peanut Butter Layer:

  • 1 cup creamy peanut butter
  • 4 Tablespoons salted butter
  • 3 Tablespoons half and half
  • cups powdered sugar sifted

Brownies:

  • 15.25 ounce box brownie mix prepared according to the box instructions
  • 1 cup semi-sweet chocolate chips

Instructions
 

  • Preheat the oven to 350 degrees Fahrenheit and prepare a 9×13 inch baking pan by lining it with parchment paper and lightly spraying the paper with cooking spray.
  • Place the creamy peanut butter and salted butter in a medium sized microwavable bowl and microwave for 30-45 seconds or until the butter has melted.
  • Stir the two ingredients together until completely combined.
  • Pour in the half and half and stir.
  • Gradually stir in the powdered sugar until completely incorporated. The mixture should end up with a consistency similar to a soft cookie dough.
  • Once the peanut butter mixture is finished, set the bowl aside while you make the brownie batter.
  • In a large bowl, prepare the brownie batter according to the box instructions.
  • Fold in the semi-sweet chocolate chips and stir to combine.
  • Evenly drop spoonfuls of brownie batter and the peanut butter mixture into the pan, making sure to alternate until you have covered the bottom of the pan.
  • Use a spoon or knife to gently combine the mixtures together to form a marbled pattern. Do not overmix or you will lose the marbling effect.
  • Bake in the oven for 35-40 minutes or until the brownie edges are baked and the center has set.
  • Allow to cool completely, or for about 30 minutes to 1 hour, before cutting and serving.

Jenn’s Notes

Storage:
  • To Store: Make sure to cover or wrap your Peanut Butter Brownies for maximum freshness and storage. Individually wrapped brownies will last for 1-2 days at room temperature or up to 4 days in the refrigerator.
  • To Freeze: You can freeze these brownies for 1-2 months and thaw overnight in the refrigerator before serving. 
Tips:
  • Line the pan with parchment paper for easy removal. Once the brownies have cooled, you can lift the whole batch right out of the pan using the paper.
  • Use a commercial brand of peanut butter that is fully combined/emulsified. I do not recommend using a “natural” peanut butter because the oil tends to separate.
  • Make sure your peanut butter is creamy because crunchy peanut butter is difficult to work with.
  • When swirling the peanut butter into the brownie batter, less is more. If you swirl too much, you will mix the peanut butter into the batter.
  • These Peanut Butter Brownies are fun to change up if you feel like doing so. Here are some of my favorite ways to change them:
    1. Use Reese’s Peanut Butter Cups or Reese’s Pieces in the brownies instead of the chocolate chips. Chop the cups up roughly before you add them to the brownie mix. You can also sprinkle some on top after the brownies come out of the oven if you would like!
    2. Drizzle the brownies with melted peanut butter or a sprinkle of sea salt when they come out of the oven.

Nutrition Info

Calories: 471kcal | Carbohydrates: 56g | Protein: 8g | Fat: 25g | Saturated Fat: 9g | Polyunsaturated Fat: 3g | Monounsaturated Fat: 10g | Trans Fat: 1g | Cholesterol: 12mg | Sodium: 232mg | Potassium: 213mg | Fiber: 2g | Sugar: 40g | Vitamin A: 137IU | Vitamin C: 1mg | Calcium: 25mg | Iron: 2mg

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Comments

    1. I used semi-sweet – but you could use milk chocolate if you prefer. I just find that too sweet.