Make the Cake Batter
Preheat oven to 350°F (no fan). Grease and line three 8″ pans. In a bowl, whisk together flour, baking powder, baking soda, both sugars, and salt. In another bowl, whisk eggs, oil, buttermilk, and sour cream. Combine dry and wet ingredients in two additions, mixing gently.

Bloom Cocoa Powder
In a small bowl, mix cocoa powder and instant coffee with boiling water until smooth and shiny. Pour into the cake batter and fold gently until fully combined.

Bake the Cake
Divide batter between the prepared pans. Bake for 22–24 minutes, or until a toothpick comes out with moist crumbs. Cool in pans 20 minutes, then transfer to a rack and chill for 1 hour.

Make the Frosting
Melt chocolate and corn syrup in a saucepan on low. In a stand mixer, beat cream cheese, cocoa, powdered sugar, and salt until smooth. Add heavy cream and whip just until fluffy. Slowly add melted chocolate while mixing. Let frosting cool 30 minutes until spreadable.

Assemble the Cake
Trim cake domes. Layer with frosting between each cake. Crumb coat the cake, chill 20 minutes, then frost fully. For a shiny finish, use a hair dryer on low 12 inches away from the cake.