Heat a skillet over medium-high heat and add the lean ground beef. Cook for about 5-6 minutes, breaking it up until browned. Mix in taco seasoning and any optional vegetables. Allow to simmer until fully cooked.

Roll out the pie crusts on a floured surface to about 1/8-inch thickness. Use a ghost-shaped cookie cutter to cut out ghost shapes; preheat the oven to 425°F.

Place half of the ghost-shaped crusts on a baking sheet. Spoon a portion of taco filling onto each crust, add shredded cheese, and cover with matching ghost cutouts.

Cut small holes in the top pieces for steam to escape. Seal the edges and brush with egg wash or milk for a golden finish.

Bake in the preheated oven for 10-14 minutes, or until puffed and golden brown. Watch closely to avoid burning.

Let the pies cool for a few minutes before serving warm with salsa or guacamole for dipping.