In a large skillet over medium heat, brown the lean ground beef for about 5-6 minutes until fully cooked. Sprinkle in taco seasoning, stirring in optional shredded carrots and chopped bell peppers or baby spinach. Cook for an additional 2-3 minutes until the vegetables are tender, then remove from heat to cool.

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

On a lightly floured surface, roll out the refrigerated pie crusts until they are about 1/8-inch thick. Use ghost-shaped cookie cutters to cut out shapes.

Place half of the ghost shapes on the prepared baking sheets. Add a generous spoonful of taco filling and sprinkle with shredded Mexican cheese.

Cut small holes in the remaining ghost shapes to create faces. Place these on top of the filled shapes and seal the edges with a fork.

Whisk together the egg with a splash of milk. Brush the tops of each pie with this mixture.

Bake for 10-14 minutes, or until golden brown. Keep an eye on them towards the end to avoid burning.

Let the pies cool for a few minutes and serve warm with salsa and guacamole.