In a medium bowl, stir the cherry pie filling and optional Kirsch together. Set aside.

Cut the store-bought chocolate cake into 1-inch cubes.

In a large, chilled mixing bowl, beat the very cold heavy cream, sifted powdered sugar, and vanilla extract with an electric mixer until stiff peaks form.

Assemble Layer 1: Place half of the chocolate cake cubes in the bottom of a large trifle bowl.

Assemble Layer 2: Spoon half of the gooey cherry pie filling mixture over the cake.

Assemble Layer 3: Spread one-third of the whipped cream over the cherries.

Assemble Layer 4: Repeat with the remaining half of the chocolate cake cubes.

Assemble Layer 5: Spoon the remaining half of the cherry pie filling over the second cake layer.

Assemble Layer 6: Spread another one-third of the whipped cream on top.

Assemble Layer 7: Top the trifle with the final one-third of the whipped cream, spreading it or creating decorative swirls.

Garnish: Sprinkle with chocolate shavings (made with a vegetable peeler) and dot with maraschino cherries.

Cover with plastic wrap and chill for at least 4 hours, or preferably overnight, to allow the flavors to meld and the trifle to set.