The dynamic duo returns in brownie form: chocolate and peanut butter. These fudgy dessert bars combine rich chocolate batter with chopped peanut butter cups folded inside and a creamy peanut butter frosting on top for the perfect balance of flavors.
I’m more of a straight chocolate baker, but add Reese’s and I’m sold. These brownies are made from scratch, reliably fudgy, and easy to share. They’re a great treat for gatherings, holidays, or any time you want a decadent dessert with a peanut butter twist.
Table of Contents
Why You’ll Love This Recipe
- The perfect pairing. Peanut butter and chocolate are a classic combination that works every time.
- Trustworthy base. The recipe uses a tried-and-true fudgy brownie batter that consistently delivers.
- Fudgy texture. Dense and chocolate-forward, these brownies have a rich, chewy center.
- Extra peanut butter flavor. Chopped peanut butter cups in the batter and a creamy peanut butter frosting on top double down on flavor.
- Versatile. These bars are appropriate for birthdays, holidays, or any moment you want an indulgent dessert.
Ingredient Notes
- Chocolate: Choose a good-quality bittersweet chocolate for smooth melting and richer flavor.
- Cocoa powder: Use unsweetened cocoa powder for depth; any reputable brand will work.
- Espresso powder: Optional, but it enhances the chocolate flavor without adding a coffee taste.
- Peanut butter cups: Mini or chopped peanut butter cups folded into the batter add pockets of peanut-buttery candy.
- Peanut butter: For the frosting use creamy, no-stir peanut butter for a smooth texture.
- Confectioners’ sugar: Powdered sugar is used to sweeten and stabilize the frosting.
See the recipe card below for exact measurements and full ingredient details.
Recipe Variations
Switch the frosting or mix-ins. For deeper chocolate flavor, use chocolate buttercream instead of peanut butter frosting. Try Reese’s Pieces, peanut butter chips, or chopped candy bars as alternative mix-ins.
Add a peanut butter swirl. After spreading the batter in the pan, drop teaspoons of peanut butter on top and gently swirl with a knife for a marbled effect—avoid over-mixing.
Make a larger batch. Double the recipe and bake in a 9×13-inch pan to serve a crowd; baking time will be similar.
How to Make Peanut Butter Brownies
- Melt the chocolate and butter using a makeshift double boiler (or microwave carefully). Whisk in cocoa powder and espresso powder, then let cool slightly.
- Beat eggs and sugar until pale and slightly fluffy. Add vanilla and salt, then fold in the chocolate mixture until combined.
- Stir in the flour just until combined, then fold in the chopped peanut butter cups.
- Spread the batter in a parchment-lined 8×8-inch pan and bake at 350°F for about 25 minutes. Cool completely before frosting.
- Make the frosting by beating peanut butter and butter until smooth. Add confectioners’ sugar, then vanilla and milk, mixing until smooth and spreadable.
- Spread the frosting over completely cooled brownies, slice, and serve.
Expert Tips
Weigh ingredients when possible for consistent results. If you don’t have a scale, spoon and level flour into the measuring cup.
Use quality chocolate for better flavor and smoother melting—this makes a noticeable difference in fudgy brownies.
Avoid over-baking to keep the center dense and fudgy. Remove when the top looks shiny and the edges are set; the brownies will finish as they cool.
Choose creamy, no-stir peanut butter for smooth frosting. If oil separates in the jar the frosting can become too thin.
Clean your knife between cuts for neat slices and a better presentation.
Make Ahead and Storage Tips
Make ahead: Bake the brownies up to 24 hours in advance and keep them covered at room temperature before frosting. The frosting can be made up to 3 days ahead and stored in the refrigerator; bring to room temperature before spreading.
Storage: Frosted brownies keep at room temperature for up to 3 days or in the refrigerator for up to 5 days in an airtight container.
Freezing: Wrap cooled brownies tightly in plastic wrap and foil and freeze up to 3 months. If frozen with frosting, flash-freeze for about an hour so the frosting firms first, then wrap. Thaw in the refrigerator before bringing to room temperature to serve.
Recipe FAQ
Bake slightly under the usual time so the center stays dense. For an 8×8 pan this is typically around 25 minutes. Accurate measurements help—too much flour makes dry, cakey brownies.
Yes, but you’ll need to add oil for texture: substitute 1/2 cup butter with 1/4 cup peanut butter plus 1/4 cup oil.
Crumbly brownies often result from over-mixing (too much air) or cutting before they’ve completely cooled.
Yes, almond butter can be substituted for peanut butter in the frosting or where specified.
Related Recipes
If you enjoyed this recipe, try these treats next!
Peanut Butter Chocolate Bars with Shortbread Crust
Cookie Dough Oreo Brownies
Peanut Butter Nutella Cookies
Banana Cupcakes with Peanut Butter Frosting
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Equipment
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1 Kitchen scale
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1 8×8 metal baking pan
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Mixing bowls
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Stand mixer or electric mixer
Ingredients
Brownies
- 1 cup (200 g) plus 2 tablespoons good quality bittersweet chocolate, chopped or chocolate chips
- ½ cup (113 g) unsalted butter, cut into quarters
- 3 tablespoons (18 g) unsweetened cocoa powder
- ½ teaspoon espresso powder (optional)
- 3 large eggs, room temperature
- 1 ¼ cups (250 g) granulated sugar
- 2 teaspoons pure vanilla extract
- ½ teaspoon salt
- 1 cup (125 g) all-purpose flour
- 1 cup (170 g) coarsely chopped peanut butter cups
Peanut Butter Frosting
- ⅔ cup (150 g) creamy peanut butter
- 6 tablespoons (85 g) unsalted butter, room temperature
- 1 cup (120 g) confectioners’ sugar, sifted
- ½ teaspoon vanilla extract
- 1 tablespoon milk (add more 1 tsp at a time for thinner frosting)
Instructions
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Preheat oven to 350°F. Line an 8×8-inch pan with parchment paper and lightly grease.
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Melt chocolate and butter in a makeshift double boiler over low heat, stirring occasionally. Remove from heat and whisk in cocoa and espresso powder; let cool slightly.
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Beat eggs and sugar for 1 minute until pale. Add vanilla and salt, then slowly pour in the chocolate mixture while mixing on low.
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Remove from mixer and fold in flour until just combined, then fold in chopped peanut butter cups. Do not over-mix.
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Spread batter in the prepared pan and bake 25 minutes, until the top is shiny and edges are set. Cool on a wire rack to room temperature, about 2 hours.
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For the frosting, beat peanut butter and butter until smooth. Add confectioners’ sugar, then vanilla and milk; mix until spreadable. Add milk 1 teaspoon at a time to adjust consistency.
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Spread frosting over cooled brownies. Slice and serve.
Notes
Peanut butter: Use no-stir creamy peanut butter for best frosting texture.
Storage: Keep in an airtight container at room temperature for 3 days or refrigerated for up to 5 days.
Freezing: Flash-freeze frosted brownies for 1 hour, then wrap tightly and freeze up to 3 months. Thaw in the refrigerator before bringing to room temperature.