FOR THE CAKE:
- 2 cups all-purpose flour
- 2 cups granulated sugar
- 1 teaspoon baking soda
- 1/2 teaspoon salt
- 1/2 cup (1 stick) unsalted butter
- 1 cup water
- 1/2 cup creamy peanut butter
- 1/2 cup vegetable oil
- 2 large eggs, at room temperature
- 1/2 cup milk, at room temperature
- 1 teaspoon vanilla extract
FOR THE FROSTING:
- 1/2 cup (1 stick) unsalted butter
- 1/2 cup creamy peanut butter
- 6 tablespoons milk
- 1 teaspoon vanilla extract
- 3 cups powdered sugar
- 1/2 cup roasted peanuts, for topping
PREPARATION
- Preheat oven to 350°F and grease a 9×13-inch pan with butter or nonstick spray.
- In a large bowl, whisk together the flour, sugar, baking soda, and salt. Set aside.
- In a large saucepan, heat the butter and water until it comes to a boil. Remove from heat and whisk in peanut butter and oil until smooth.
- Let cool 2 minutes, then whisk in eggs, milk, and vanilla until well incorporated.
- Add to dry ingredients and mix until smooth. Pour batter into prepared pan and bake until a toothpick inserted into the center comes out clean, 40-45 minutes.
- Set pan on a wire rack to cool while you make the frosting:
- To a medium saucepan, add the butter, peanut butter, and milk and bring to a rolling boil.
- Remove from heat and stir in vanilla, followed by powdered sugar, 1 cup at a time.
- Whisk until smooth, reheating a bit if needed, then pour over cake. If frosting is stiff, add a bit more milk.
- Working quickly, spread frosting evenly over cake and top with peanuts. Slice, serve, and enjoy!