Combine the sugar, flour, cocoa powder, baking soda, baking powder, and salt into a bowl. Stir together with a whisk until evenly combined

Add the vanilla, eggs, buttermilk, and oil and stir until combined

Once combined, add the hot coffee. Stir quickly to ensure the hot coffee is evenly distributed. The batter will be very thin

Pour the batter into a greased and floured 16”x10” sheet pan and cook for ~15-20 minutes (ovens vary so test with a toothpick in the center and remove when it comes out clean) 350 F – make sure a toothpick comes out clean

Set aside to cool

Peanut Butter Buttercream:

Cut the softened butter in tablespoon pieces.

Add 2 inches of water into a saucepan that fits the bowl of a stand mixer on top without touching the water. After the water is simmering, add the sugar, egg whites, and salt. Whisk to combine and continue to simmer, ensuring the water does not touch the bowl. Keep heating the mixture until the sugar is dissolved (it will be about 120 degrees)

Place the bowl in the stand mixer and whisk on high speed until mixture is thick and glossy. It should hold very stiff peaks.

Reduce the speed of the mixer to medium and add the butter one tablespoon at a time until incorporated. Reduce the speed to low and add the peanut butter. Turn up the speed to medium until well incorporated. Set aside

When all components are ready, spread a layer of the peanut butter icing in between each layer. Coat the entire cake with the remaining peanut butter icing and top with peanut butter cups