Heat Grill: Set your Ninja Woodfire Pro Connect XL Grill function to bake, temperature to 325F degrees and time to 30 minutes.
Prep: Cut each cheese slice in half. Remove the pastry from the packaging. Unfold and roll slightly to flatten.
Layer: Place the cheese slices on the puff pastry. Use a pizza cutter or knife to cut around the slices, leaving about 1/4 inch extra on all sides.
Prep Pan: Lay the pastry slices and cheese on a small sheet pan lined with parchment paper.
Add Filling: Add about 1 tablespoon brisket on top of each cheese slice and spread around. Continue to leave an edge all the way around. Drizzle with BBQ sauce.
Egg Wash: Mix the egg with a little water. Brush along the edges of the pastry.
Top: Cut the remaining pastry into rectangles the same size as the bottom Place on top of the brisket. Crimp closed with a fork.
Lattice or Mummy Strips: Cut the remaining pastry into thin long strips. Lay the strips across the brisket, criss-crossing some to make it look like a mummy. Leave an opening near the top for the eyes. Cut away any overhang so the strips are the same width as the rectangle. Crimp the edges with a fork.
Brush: Brush the top with egg wash.
Bake: Place the pan on the preheated grill and bake for 15 minutes or until golden brown.
Serve: Remove from the grill and serve. If making mummy hand pies, add one to two googly eyes to each tart.