Special equipment: A 4-inch round cutter; a ruler
Preheat the oven to 375 degrees F.
Use a 4-inch round cutter to cut out a hole in the exact center of two of the cakes. Using an offset spatula or butter knife, add a 1/4-inch layer of the frosting to one of the whole cakes, which will become the bottom layer. Then place one cake with a hole in it over the top of the bottom layer. Frost that cake with a 1/4-inch layer of frosting. Place the second cake with the hole over the top and frost that cake with a 1/4-inch layer of frosting. Set the remaining whole cake aside for a later use. Measure the height of the barrel created in the cake center.
Spray a baking sheet with nonstick cooking spray. Dust flour on a clean surface and roll out the pie crust to 1/8-inch thick. Use a ruler to cut 15 strips of pie dough, 1-inch wide and the height of the cake, and then use the 4-inch round cutter to cut a round of pie dough. Transfer the pie strips and round to the prepared baking sheet. Bake the dough until golden, 8 to 10 minutes.
Frost the inside of the barrel of the cake. Drop the pie round into the bottom of the barrel to create the bottom. Lightly press the baked pie strips into the sides of the barrel directly next to each other until the barrel is fully formed. Pour the cherry pie filling into the center of the barrel. Finally place the remaining whole cake on top to cover. Cover the entire cake with the remaining chocolate frosting. Dust with confectioners' sugar to serve.
In a stand mixer fitted with a paddle attachment, combine the flour, sugar and salt. Slowly drop in the cubed butter and mix until the mixture resembles wet sand. In a small bowl whisk together the egg yolks and heavy cream, then pour the mixture into the bowl of the stand mixer and whip until just combined. Turn the dough out onto a clean cutting board and cut in half. Using your hands, gently push each half of dough into a disc and wrap each in plastic wrap. Refrigerate for at least 6 hours or up to overnight.