Preheat your oven to 350°F (175°C) and prepare three 9-inch round pans by greasing them and lining the bottoms with parchment paper.

In a large mixing bowl, combine the granulated sugar, all-purpose flour, cocoa powder, baking powder, baking soda, and salt. Whisk until evenly blended.

Make a well in the center of the dry mixture, add the eggs, buttermilk, canola oil, and vanilla extract, then mix until smooth.

Stir in the hot brewed coffee and instant espresso powder until well incorporated.

Evenly divide the batter among the prepared pans and bake for 26-30 minutes, until a toothpick comes out clean.

Remove the cakes from the oven, let cool for 10-15 minutes, then turn out onto a wire rack to cool completely.

For the frosting, beat the unsalted butter until fluffy, gradually add powdered sugar, then add heavy whipping cream (or Kahlua) until smooth.

To assemble, level the cake layers if needed, frost between layers, on top, and around the sides.