1) Preheat oven to 350 degrees F. In a small saucepan, melt butter over medium-low heat. Stir in cocoa powder. When butter is melted, stir in boiling water and let bubble for a few minutes.
2) In a large bowl, whisk together flour, sugar, and salt. In a separate smaller bowl, whisk together buttermilk, eggs, vanilla and baking soda.
3) Pour chocolate mixture into flour mixture and whisk together. Then stir in the buttermilk and eggs mixture. Mix until batter is smooth and then pour into a 12×12 or similar sized sheet pan.
4) Bake sheet cake at 350 degrees for 20 minutes until a tester comes out clean from the center. If you use a different sized baking sheet, your baking time might change.
5) Meanwhile, combine cherries, sugar, and bourbon in a pot over low heat. Once sugar is dissolved and cherries are steaming, remove from heat and let cool.
6) When cake is done, spoon cherry mixture over the top of the cake. Let the cake cool to room temperature before adding whipped cream.
7) Whisk together whipped cream with vanilla and sugar and spread evenly over cooled chocolate cake. Garnish with shaved chocolate.