Peanut Butter Sheet Cake with Peanut Butter Frosting

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Here’s a delicious, rich, and moist Peanut Butter Sheet Cake with Peanut Butter Frosting recipe that’s perfect for peanut butter lovers. It’s easy to make, feeds a crowd, and is absolutely irresistible!

🥜 Peanut Butter Sheet Cake with Peanut Butter Frosting

Ingredients

For the Cake:

  • 2 cups all-purpose flour

  • 2 cups granulated sugar

  • 1 teaspoon baking soda

  • ½ teaspoon salt

  • 1 cup water

  • 1 cup creamy peanut butter

  • ½ cup unsalted butter

  • ½ cup vegetable oil

  • 2 large eggs

  • ½ cup buttermilk

  • 1 teaspoon vanilla extract

For the Frosting:

  • ½ cup unsalted butter

  • ½ cup creamy peanut butter

  • 6 tablespoons milk

  • 1 teaspoon vanilla extract

  • 3½ to 4 cups powdered sugar (adjust for desired consistency)

Instructions

Step 1: Prepare the Cake Batter

  1. Preheat oven to 350°F (175°C). Grease a 13×18-inch sheet pan or jelly roll pan.

  2. In a large mixing bowl, whisk together flour, sugar, baking soda, and salt. Set aside.

  3. In a medium saucepan, combine water, peanut butter, butter, and oil. Bring to a gentle boil over medium heat, stirring until the mixture is smooth and blended.

  4. Pour the hot peanut butter mixture over the dry ingredients and mix until well combined.

  5. In a small bowl, whisk together eggs, buttermilk, and vanilla. Stir this mixture into the batter until smooth.

Step 2: Bake the Cake

  1. Pour the batter into the prepared sheet pan and spread evenly.

  2. Bake for 18–22 minutes, or until a toothpick inserted in the center comes out clean.

  3. Once baked, remove from the oven and let it rest while you prepare the frosting.

Step 3: Make the Peanut Butter Frosting

  1. In a medium saucepan, combine butter, peanut butter, and milk. Bring to a gentle boil, stirring until smooth.

  2. Remove from heat and whisk in vanilla extract.

  3. Gradually add powdered sugar, mixing until the frosting is smooth and pourable.

  4. Immediately pour the warm frosting over the warm cake. Spread quickly with a spatula for an even layer.

Step 4: Cool and Serve

  • Let the frosted cake cool completely before cutting into squares.

  • For an extra touch, sprinkle chopped roasted peanuts on top or drizzle a bit of melted chocolate.

🍰 Tips for the Perfect Peanut Butter Sheet Cake

  • Use creamy peanut butter: Natural peanut butter can cause texture issues due to its oil separation.

  • Don’t overbake: This cake is best when moist, so keep an eye on the baking time.

  • Frost while warm: The warm frosting seeps slightly into the cake, creating that signature gooey texture.

  • Storage: Store covered at room temperature for up to 3 days or refrigerate for up to 5 days.

Flavor Variations

  • Chocolate Swirl: Add a drizzle of melted chocolate on top before the frosting sets.

  • Peanut Crunch: Mix chopped peanuts or peanut butter chips into the batter.

  • Salted Caramel Twist: Drizzle salted caramel sauce over the frosting for a sweet-salty balance.

This Peanut Butter Sheet Cake with Peanut Butter Frosting is rich, nutty, and unbelievably soft. The frosting melts into the cake, making every bite velvety and indulgent — the perfect dessert for family gatherings or potlucks!

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