Making the Cake

Preheat the oven to 350ºF. Prepare a bundt cake pans by generously greasing the sides and bottom of the pan with butter.

In a large mixing bowl, add the cake flour, baking powder, baking soda, and salt. Whisk together until completely combined. Set aside.

In a stand mixer, using the paddle attachment, cream the butter, peanut butter, and brown sugar. Mix on medium to high speed until the mixture is light and fluffy, about 3-5 minutes. Be sure to scrape the bowl down halfway through to prevent any lumps from sticking to the bottom of the mixing bowl.

Lower the mixer to slow speed and the egg yolks. Mix until the egg yolks are fully combined, about 1-2 minutes.

Add the vanilla. Mix until combined.

Add one third of the flour mixture and mix on low speed until just combined. Add half of the butter milk and mix. Add another third of the flour mixture, followed by the remaining half of the buttermilk, and finish off with the last of the flour mixture, mixing after each addition.

In a separate mixing bowl, whisk the egg whites and cream of tartar on high speed until stiff peaks begin to form, about 5 minutes.

Gently fold the egg whites and peanut butter chips into the batter until fully incorporated.

Pour the cake batter into the prepared bundt cake pan. Bake for 40-45 minutes. At the 20 minute mark of baking, cover the pan with aluminum foil to prevent the top of the cake from burning. The cake is done when a toothpick inserted comes out clean.

Remove the cake from the oven and cool in the pan for about 15 minutes before flipping out onto a wire rack.

Making the Peanut Butter Frosting

While the cake cools, start the frosting in the stand mixer. Using the paddle attachment, beat the butter and peanut butter together on medium speed until smooth, about 3-5 minutes.

Add the powdered sugar, heavy cream, vanilla and salt. Start mixing on low speed, and increase to medium speed once most of the powdered sugar has mixed in. Keep mixing until a smooth frosting begins to form, about 3 minutes.

Once the cake has completed cooled, frost with Peanut Butter Frosting and Chocolate Buttercream Frosting.

Enjoy!