1. Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. In a large bowl, sift together flour, cocoa powder, baking powder, baking soda, and salt.
3. In another bowl, beat the sugar, vegetable oil, eggs, and vanilla extract until smooth.
4. Gradually add the dry ingredients to the wet ingredients, alternating with buttermilk. Mix until just combined.
5. Stir in boiling water until the batter is smooth. Divide the batter evenly between the prepared cake pans.
6. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Allow cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

For the Cherry Filling:

1. In a saucepan, combine pitted cherries, cherry juice, sugar, and cornstarch. Cook over medium heat, stirring constantly until the mixture thickens and comes to a boil. Remove from heat and let cool.

For the Whipped Cream Frosting:

1. In a mixing bowl, beat the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.

Assembly:

1. Place one cake layer on a serving plate. Spread half of the cherry filling over the top.
2. Add a layer of whipped cream frosting over the cherry filling.
3. Place the second cake layer on top and repeat with the remaining cherry filling and whipped cream frosting.
4. Frost the top and sides of the cake with the remaining whipped cream.
5. Garnish with chocolate shavings and whole cherries.