In a skillet over medium-high heat, brown one pound of lean ground beef for about 6-8 minutes until fully cooked. Drain excess fat and mix in taco seasoning along with any optional veggies. Cook for another 2-3 minutes until softened.

Roll out one pie crust to about 1/8-inch thick. Use ghost-shaped cookie cutters to cut out an equal number of shapes for the top and bottom.

Line a baking sheet with parchment paper and lay half of the ghost shapes down. Spoon about a tablespoon of taco filling onto each shape and sprinkle shredded Mexican cheese on top. Place the remaining shapes with cut-out eyes and mouths over the filled shapes before crimping the edges.

Whisk together one egg with a splash of water or milk to create an egg wash. Gently coat the tops of the assembled hand pies.

Preheat oven to 425°F (220°C). Bake the hand pies for 10-14 minutes until golden brown. Remove and let cool before serving.