In a small bowl, dissolve the cocoa powder and cayenne with hot brewed coffee and set aside.
In the bowl of a stand mixer with paddle attachment,cream oil and sugar until well combined.
Add eggs and beat until light and creamy, about 1-2minutes. This process beats air into the mixture. Scrape paddle and bowl and beat once.
Slowly add in coffee/cocoa mixture, buttermilk, vanilla, and beat until batter is smooth. Scrape paddle and bowl and beat once.
In a separate bowl, sift flour, salt, baking soda, and baking powder. Add dry ingredients to wet and beat on low speed to incorporate. Scrape down the bowl and mix just until all ingredients are combined, do not over mix once flour is in.
Butter the bottom and sides of two 9-inch cake pans and place a round parchment circle in each. Butter the top of the parchment then sprinkle the whole inside of the parchment and pan with cocoa powder, shaking out excess. Pour batter evenly between two pans and place in the center of the oven.
Bake 30-35 minutes or until a toothpick inserted into the center comes out clean. Depending on your oven, you may need to rotate cake pans halfway through. Do not over bake.
Cool pans on wire racks for ten minutes then carefully invert the pan onto a rack to cool further.
Prepare the Frosting
Sift cocoa powder with confectioner’s sugar in a large bowl. In the bowl of a stand mixer or hand mixer, cream butter until smooth.
Add sugar and cocoa powder mixture along with buttermilk and vanilla and beat until smooth and creamy.
Add additional buttermilk or whole milk if frosting is too thick.
Place a small dollop of frosting on a cake dish to hold the cake from sliding and place one cake on the frosting. Frost the top of that layer.
Place the second cake on the first and frost the entire cake, top and sides.