Step 1: Make the Chocolate Cake

1. Preheat the oven: Preheat your oven to 350°F (175°C). Grease and flour three 8-inch round cake pans.
2. Mix the dry ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, cocoa powder, and salt. Set aside.
3. Mix the wet ingredients: In a large bowl, whisk together the eggs and granulated sugar until light and fluffy (about 2-3 minutes). Add the oil and vanilla extract, continuing to whisk until combined.
4. Add the buttermilk: Gradually add the buttermilk to the wet ingredients, mixing well.
5. Add the dry ingredients: Slowly add the dry ingredients to the wet mixture, mixing just until combined.
6. Incorporate the boiling water: Gradually pour in the boiling water and stir until smooth. The batter will be thin, but that’s expected.
7. Bake: Pour the batter evenly into the prepared pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Let the cakes cool in the pans for 10 minutes, then turn them out onto a wire rack to cool completely.

Step 2: Prepare the Whipped Cream

1. Whip the cream: In a chilled mixing bowl, beat the heavy cream with powdered sugar and vanilla extract until stiff peaks form. Be careful not to overwhip the cream—soft, billowy peaks are perfect.

Step 3: Assemble the Cake

1. Level the cakes: Once the cakes have completely cooled, carefully level the tops with a serrated knife if necessary, so they are even.
2. Soak the cake layers: Lightly drizzle some of the reserved cherry juice (or Kirsch, if using) over the cake layers to give them moisture and a bit of flavor.
3. Layer the cake: Place one layer of the chocolate cake on a serving platter. Spread a layer of whipped cream over the cake, then top with a portion of the drained cherries.
4. Repeat the layers: Place the second layer of cake on top, followed by more whipped cream and cherries. Add the final layer of cake, and then cover the entire cake with the remaining whipped cream.
5. Decorate: Garnish the top and sides of the cake with chocolate shavings or curls, and place a few whole cherries on top for a classic Black Forest Cake look.

Step 4: Chill and Serve

1. Chill the cake: Refrigerate the cake for at least 2-3 hours, preferably overnight, to let the flavors meld together and allow the cake to set.
2. Serve: Slice and serve your delicious homemade Black Forest Cake chilled with a cup of coffee or a glass of dessert wine.