01 - Preheat oven to 350°F. Grease and line two 9-inch round cake pans with parchment paper.
02 - In a large bowl, sift together flour, baking powder, baking soda, salt, and cocoa powder.
03 - In another large bowl, whisk sugar, vegetable oil, eggs, and vanilla extract until smooth.
04 - Add dry mixture to wet ingredients and stir until just combined.
05 - Gradually mix in milk followed by hot coffee until batter achieves a smooth, thin consistency.
06 - Divide batter evenly into prepared pans and bake 30 to 35 minutes or until a toothpick inserted in the center comes out clean.
07 - Allow cakes to cool in pans for 10 minutes, then transfer to wire racks to cool completely.
08 - Beat butter and cocoa powder until creamy. Gradually add powdered sugar, milk, vanilla extract, and salt, beating until smooth and fluffy. Add milk as needed for spreadability.
09 - Place one cake layer on a serving plate and spread frosting on top. Add second layer and cover top and sides with remaining frosting.