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Buttermilk Brownies with Peanut Butter Frosting Recipe

These classic Buttermilk Brownies are rich and fudgy and topped with a creamy peanut butter frosting (my favorite combination!). This recipe is perfect for a party because it makes an entire sheet pan of brownies.
Prep Time15 mins
Cook Time18 mins
Total Time33 mins
Course: Dessert
Cuisine: American
Keyword: best brownies, Brownies, chocolate brownies, Reese's Brownies
Servings: 24
Calories: 380kcal


  • Baking Sheet
  • Wooden Spoon
  • Mixing bowls


  • 2 cups flour
  • 2 cups sugar
  • ½ cup butter
  • ½ cup shortening
  • 1 cup water
  • ¼ cup cocoa
  • ½ cup buttermilk
  • 2 eggs
  • 1 teaspoon baking soda
  • 1 teaspoon vanilla


  • 8 ounces cream cheese 1 package, softened
  • ½ cup unsalted butter softened
  • 4 cups powdered sugar
  • cup creamy peanut butter


  • 1 cup chocolate chips melted
  • ½ cup Reese's pieces


  • In a large mixing bowl, combine the flour and the sugar. Set aside.
  • In a medium saucepan, combine butter, shortening, water, and cocoa. Stir and heat to boiling.
  • Pour boiling mixture over the flour and sugar in the bowl.
  • Add the buttermilk, eggs, baking soda, and vanilla to the mixing bowl. Mix well using a wooden spoon or high speed on an electric mixer.
  • Pour into a well-greased baking sheet (17.5" x 11") pan.
  • Bake at 400 degrees for 15-18 minutes or until brownies test done in center.
  • To make the frosting, mix cream cheese and butter together with a mixer until completely incorporated. Add in powdered sugar and peanut butter and mix well. If it's too thick, thin it out with a little bit of milk. If it's too thin, add some more powdered sugar.
  • Spread frosting on cooled brownies.
  • If desired, drizzle melted chocolate chips over frosting and sprinkle Reese's pieces candies on top.


  • To make your own buttermilk, simply mix together 1/2 cup milk with 2 teaspoons white vinegar or lemon juice (either one will work). Let the milk sit for at least 5 minutes before adding it into the mixture. That’s it!


Calories: 380kcal | Carbohydrates: 51g | Protein: 5g | Fat: 19g | Saturated Fat: 8g | Trans Fat: 1g | Cholesterol: 40mg | Sodium: 172mg | Potassium: 110mg | Fiber: 1g | Sugar: 40g | Vitamin A: 326IU | Vitamin C: 1mg | Calcium: 36mg | Iron: 1mg