For the cake: Preheat oven to 350°F and prepare two 9-inch round cake pans with parchment paper and butter.
Combine the sugar, flour, cocoa powder, baking soda and salt together in a large bowl and whisk until combined, set aside.
Whisk together, eggs, buttermilk, oil and vanilla until well combined. Add the egg mixture to the dry ingredients and whisk until smooth. Slowly add the hot coffee and rum to the batter and whisk until totally blended and smooth, about 2 minutes. The batter will be quite runny.
Divide the batter into the prepared pans and bake for about 25 minutes or until set when tested with a toothpick. Cool completely.
For the cherry filling and topping: Place the cherries and kirsch in a sauce pot.
Whisk together the sugar and cornstarch in a small bowl and then add to the cherries.
Add the sugar mixture to the cherries and cook over low heat until the cherries come to a boil and the liquid thickens and is transparent, about 10 minutes. If you are using fresh cherries, you will want to cook them until the fruit is slightly tender. Transfer to a bowl and cool to room temperature.
To assemble the cake: Whip the cream, powdered sugar and vanilla to stiff peaks.
Place one layer of the cake on a serving platter. Spread half of the whipped cream over the top. Distribute half the cherries over the cream. Repeat with the next layers of cake, cream and cherries. Serve cherry chocolate cake immediately or place it in the refrigerator.