Preparation Steps

• Preheat the oven to 350°F (175°C). Grease and flour a 9-inch round cake pan or line with parchment paper.
• In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
• In a large bowl, beat the unsalted butter and granulated sugar until light and fluffy, about 2 to 3 minutes.
• Add 1 cup peanut butter to the butter-sugar mixture and mix until well combined.
• Add the eggs one at a time, beating briefly after each addition, then mix in the vanilla.
• With the mixer on low speed, add the dry ingredients in three additions alternately with the milk, beginning and ending with the dry ingredients. Mix until just combined; do not overmix.
• Pour the batter into the prepared pan, smooth the top, and bake in the preheated oven for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean.
• Remove the cake from the oven and allow it to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before frosting.
• To make the frosting: in a bowl, beat the 0.25 cup unsalted butter and 0.5 cup peanut butter until smooth. Gradually add the powdered sugar, beating until combined. Add heavy cream 1 tablespoon at a time to reach desired consistency and mix in the 0.25 teaspoon salt.
• When the cake is completely cool, spread the peanut butter frosting evenly over the top. Slice and serve.