Preheat the oven to 350 degrees F. Grease three 8-inch (or 9 inch) round cake pans, or line with parchment paper, then butter/spray with cooking spray.

In a medium size bowl combine the flour, sugar, unsweetened cocoa powder, baking soda, baking powder and salt. Set aside.

In the bowl of a stand mixer (or use a hand held mixer) beat together the eggs, buttermilk, greek yogurt, canola oil and vanilla until smooth. Slowly add the dry ingredients to the wet ingredients with the mixer on low until there are no longer any clumps of flour. Add the hot coffee and mix until combined. Batter should be pourable, but not super thin.

Pour the batter among the 3 cake pans and bake 20 to 25 minutes, until the tops are just set and no longer wiggly in the center. Remove and let cool five minutes, then run a knife around the edges of the pan. Grab 3 large flat plates, line them with wax or parchment paper and invert the cakes onto the paper lined plates. Cover and let the cakes cool completely before frosting.

In a dry, large deep heavy skillet cook the sugar over moderately high heat, stirring constantly with a heat proof rubber spatula until the sugar is melted and turns a deep golden caramel, remove the skillet from the heat and add the chunks of butter one by one, whisk until combined. The caramel will bubble, this is ok. Now slowly add the cream and then whisk until combined. Return the pot to the heat and, cook the mixture over moderate heat, stirring until the caramel has thickened, about 3-5 minutes. Remove from the heat, if using, add the bourbon + a pinch of salt. Set the caramel aside to cool.

Bring a large pot (big enough to place your mixing bowl over top) of water to boil. In the bowl of a stand mixer whisk the egg whites and sugar together. Place the bowl of the stand mixer over the pot of boiling water and cook, stirring often, until the egg whites are very warm to the touch and the sugar has dissolved, remove the bowl from the heat. Whip the egg whites on high until stiff peaks form. Allow the egg whites to cool before continuing.

Once cool, add the butter, caramel, melted milk chocolate and cocoa powder. Beat until combined and fluffy.

Place 1 layer, flat side up, on a plate or cake stand. With a knife or offset spatula, spread the top with frosting. Place the second layer on top, rounded side up, and spread the frosting evenly on the top. Finally, add the third cake layer and frost the top and sides of the cake. Place the cake in the fridge to chill for at least an hour.

Meanwhile, make the ganache. In a microwave safe bowl add the chocolate and cream. Microwave on high for 30 second intervals, stirring between each until melted. Stir in the Kahlua. Allow the ganache to cool 10 minutes, and then pour the ganache onto the middle of the chilled cake and spread to just the sides, allow the ganache to drip down the sides of the cake. Place the cake in the fridge, preferably overnight, but at least 1 hour. Allow the cake to sit at room temp for at least an hour before serving. If desired, drizzle the cake with any remaining caramel and decorate with [homemade | https://www.halfbakedharvest.com/frozen-hot-fudge-peanut-butter-swirled-pretzel-macarons/] or store bought macarons. Can also decorate with sprinkles, chocolate curls or whatever your heart desires.