Preheat the oven to 350°F (175°C). Grease a 9-inch round cake pan and line the bottom with parchment paper.

In a large mixing bowl, sift together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.

In a separate mixing bowl, whisk together the milk, vegetable oil, vanilla extract, and eggs.

Gradually mix the wet ingredients into the dry ingredients, until well combined.

Slowly stir in the boiling water, until the batter is smooth.

Pour the batter into the prepared cake pan and bake for 25 minutes, or until a toothpick inserted in the center comes out clean.

Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.

In a saucepan, mix the cherry pie filling, cornstarch, and water. Cook over medium heat, stirring constantly, until the filling thickens. Remove from heat and let it cool.

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

Cut the cooled cake in half horizontally with a serrated knife.

Place one layer of the cake on a serving platter and spread half of the cherry filling on top.

Add a layer of whipped cream on top of the cherry filling.

Place the second layer of the cake on top and repeat the layers of cherry filling and whipped cream.

Use the offset spatula to smooth the whipped cream on the sides and top of the cake.

Garnish with chocolate shavings and maraschino cherries.

Refrigerate for at least 2 hours before serving.

Serve and enjoy this delicious and decadent Black Forest Cake!