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Easy Decadent Reese's Peanut Butter Cup Brownies

Ooey-gooey, chocolatey squares of happiness featuring Reese's Peanut Butter Cups, made ridiculously easy with a box mix base. These brownies disappear faster than you can say "peanut butter"!
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Cook Time 25 minutes
Course: Baked Goods, Dessert
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

For the Brownies
  • 1 box brownie mix (18 oz), your favorite brand that calls for eggs, water, and oil
  • Ingredients called for on the box Usually eggs, water, and vegetable oil. Just follow the package instructions for these.
  • 15 full-size Reese's Peanut Butter Cups unwrapped
For the Peanut Butter Frosting
  • 3/4 cup creamy peanut butter
  • 1/2 cup unsalted butter at room temperature
  • 2 1/4 cups confectioners sugar Also known as powdered sugar.
  • 4 tbsp heavy cream
  • 1 1/2 tsp vanilla extract

Equipment

  • 9x13 inch Baking Dish
  • Parchment Paper
  • Large bowl
  • Mixer

Method
 

  1. Step 1: Preheat your oven to 350°F (175°C). Grab a 9×13-inch baking dish and line it with parchment paper, leaving some overhang on the sides.
  2. Step 2: Make your brownie batter by following the instructions exactly as they are on your box mix. Whisk in the eggs, water, and oil until combined. Do not overmix.
  3. Step 3: Pour about two-thirds of the brownie batter into your prepared baking dish and spread it out evenly across the bottom.
  4. Step 4: Arrange the 15 unwrapped Reese’s Cups in a single layer right over the batter. You can gently press them in a tiny bit.
  5. Step 5: Carefully spoon the remaining brownie batter over the top of the Reese's layer, spreading it out gently to cover all the peanut butter cups.
  6. Step 6: Pop the dish into your preheated oven. Bake for 25–30 minutes. You're looking for a toothpick inserted near the center (avoiding a Reese's Cup) to come out with just a few moist crumbs attached.
  7. Step 7: Let the brownies cool completely in the pan on a wire rack before frosting.
  8. Step 8: While the brownies are cooling, make the frosting. In a large bowl, beat the creamy peanut butter and the softened butter together until smooth and creamy.
  9. Step 9: Gradually add the confectioners sugar, a little at a time, mixing until incorporated. Scrape down the sides of the bowl as needed.
  10. Step 10: Pour in the heavy cream and vanilla extract. Beat on medium-high speed for about 2 minutes until it transforms into a light, fluffy peanut butter frosting.
  11. Step 11: Once your brownies are totally cool, use the parchment paper overhang to carefully lift the whole slab out of the baking dish and place it on a cutting board or flat surface.
  12. Step 12: Spread the peanut butter frosting evenly all over the top of the cooled brownies.
  13. Step 13: For cleaner slices, you can pop the frosted brownies into the fridge for 30 minutes to an hour before cutting into squares (a warm knife helps!).
  14. Step 14: Serve and enjoy!

Notes

Do not overbake the brownies; check around 25 minutes. Let them cool completely before frosting. Use parchment paper to easily lift the brownies from the pan. For clean cuts, chill the frosted brownies before slicing and wipe your knife between cuts. Bake brownies a day in advance and store airtight; make frosting just before assembly. Store leftovers in an airtight container at room temperature for 3-4 days, or in the refrigerator if it's warm or you prefer a firmer bite. You can substitute different candies like Rolo or mini peanut butter cups. Add chocolate chips to the batter or swirl melted chocolate/peanut butter over the frosting. Sprinkle chopped peanuts or mini chocolate chips on top for texture. Use a favorite homemade brownie recipe instead of the mix if desired.