In a medium skillet over medium-high heat, add the lean ground beef and cook for about 5-7 minutes until it browns completely. Drain excess fat if necessary, then stir in the taco seasoning and any optional shredded carrot or chopped bell pepper. Continue cooking for another 5 minutes, breaking the meat into small pieces, and remove from heat once it's well combined and fragrant.

On a lightly floured surface, take the defrosted pie crusts and roll them out gently to prevent tears. Using a ghost-shaped cookie cutter (or a knife), cut out ghost shapes, ensuring each pie will have a matching top and bottom. Aim for at least 12-14 cut-outs to have enough pairs for your Ghost Mini Taco Pies.

On a lined baking sheet, lay out half of the ghost cut-outs. Using a small spoon, add a generous spoonful of the prepared taco filling to the center of each ghost shape. Top each filling portion with a sprinkle of shredded Mexican cheese, ensuring not to overfill as this could cause bursting during baking.

Take the remaining ghost cut-outs and cut small openings for eyes and a mouth using a knife to give them their spooky appearance. Carefully place these ghost tops over the filled pies and press the edges firmly together, sealing them with a fork to create a decorative edge while ensuring no filling escapes.

Preheat your oven to 425°F (220°C). Before baking, brush the tops of the sealed Ghost Mini Taco Pies with a beaten egg to create a golden finish. Place the baking sheet in the oven and bake for 10-14 minutes, or until the pies are puffed and golden brown, providing a delightful visual cue of their readiness.

Once baked, remove the Ghost Mini Taco Pies from the oven and allow them to cool slightly on a wire rack. Serve warm alongside vibrant salsa or creamy guacamole for dipping. These spooky treats are perfect for gatherings, adding fun to any Halloween celebration!