Preheat your oven to 350°F (175°C) and grease three 9-inch round cake pans. Line the bottoms with parchment paper.

In a large mixing bowl, whisk together the granulated sugar, all-purpose flour, unsweetened cocoa powder, baking powder, baking soda, and salt until combined.

Create a well in the dry ingredients and add the large eggs, buttermilk, canola oil, and pure vanilla extract. Mix on medium speed for about 30 seconds until just combined.

Carefully mix in the hot coffee and instant espresso powder, ensuring a smooth, slightly thin batter.

Divide the batter evenly among the three prepared cake pans and bake for 26 to 30 minutes until they spring back when pressed.

Let the cakes cool in the pans for 10 to 15 minutes before transferring to a wire rack to cool completely.

For the buttercream, beat room temperature unsalted butter until creamy. Gradually add powdered sugar, heavy cream or Kahlua, vanilla extract, and salt, mixing until fluffy.

Once cooled, frost the layers and assemble the cake, ensuring each layer is level and evenly spread with frosting.