In a skillet over medium-high heat, brown the ground beef for about 5-6 minutes, stirring frequently. Drain excess fat, then add taco seasoning and optional vegetables. Cook for an additional 2 minutes, then set aside to cool slightly.

Preheat your oven to 425°F (220°C) and line two baking sheets with parchment paper.

Roll out the pie crusts until about ⅛ inch thick, then cut out 30 ghost shapes using a cookie cutter. Organize them into pairs for even baking.

On prepared baking sheets, lay half of the ghost-shaped crusts. Spoon about 1 tablespoon of filling on each, sprinkle cheese, then cover with remaining crusts. Seal edges with a fork.

Whisk together the egg with a splash of water for the egg wash and brush the tops of the assembled pies.

Bake for 10-14 minutes or until golden brown and flaky. Monitor closely towards end of cooking time.

Remove from oven and let cool for about 5 minutes before serving warm with salsa or guacamole.