Sift the dry ingredients together and set aside. Beat the sugar and butter together until creamy, about 3 minutes. Add the eggs and yolk, one at at time, beating for 1 minute in between each addition. Beat in the vanilla. The mixture will look curdled, but it will all come together, I promise. Turn the mixer on low and add the dry ingredients alternatively with the buttermilk. Start and end with the dry. Scrap down the sides of the bowl really well.

Pour the cake batter into two 9-inch pans that have been sprayed well with cooking spray and lined with parchment. Isn’t it amazing how the towel trick works? They are perfectly level. Bake the cakes in a preheated 350 degree oven for about 28 minutes, rotating halfway through baking. When they are finished, they will be golden and start to pull away from the sides of the pan. Let the pans sit on a rack for about 5 minutes, then unmold them and let them cool completely.

Now you are going to make the espresso extract. It is nothing more than combining the espresso powder and the boiling water into a bowl. Set this aside.

In a small saucepan combine the sugar and water. Bring it to a boil. Pour in into a bowl and add 1 Tablespoon of the espresso extract that we just made and the 1 Tablespoon of Kahlua. Set this aside.

Whisk together the mascarpone, sugar, vanilla, and remaining Kahlua. Whisk until blended and smooth. Beat the heavy cream in the mixer until it holds firm peaks. Gently fold the whipped cream into the mascarpone mixture using a spatula.

Now we are ready to assemble the cake. I put a few strips of parchment underneath my cake layers (but not underneath the whole thing) so that I would not get frosting all over my cake plate. When I am done decorating, these pieces will come out and the plate will still be clean. Poke some holes with a toothpick or a knife and brush the cake with the espresso syrup.

Spread a layer of the frosting over the first cake layer. Use about a cup and a quarter. Level it with an offset spatula and sprinkle with the chocolate. Add the top layer and again, poke with holes and brush with the espresso syrup.

Add 1 to 2 Tablespoons of the remaining espresso extract to the remaining frosting. Fold together.

Frost the cake with the rest of the frosting. Chill for at least 3 hours but overnight is better.

Dust the top with cocoa powder.