Preheat the oven to 350°F (175°C). Grease and flour a 9x13-inch baking pan.
In a large mixing bowl, combine the chocolate cake mix, water, vegetable oil, and eggs. Beat on medium speed for 2 minutes until well combined. Pour the batter into the prepared baking pan.
Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Allow the cake to cool in the pan for 10 minutes, then poke holes all over the top using the handle of a wooden spoon.
While the cake is still warm, spoon the cherry pie filling over the top, allowing it to fill the holes. Let the cake cool completely.
In a mixing bowl, whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form. Spread the whipped cream over the cooled cake.
Garnish with chocolate shavings or grated chocolate. Refrigerate for at least 2 hours before serving to allow the flavors to meld.