Preheat oven to 400°. Line a large, rimmed baking sheet with parchment.
In a large bowl, add beef, onion, panko, garlic, parsley, and egg. Season generously with salt and pepper. Mix ingredients together with a wooden spoon until well combined, then shape into 1” balls. Place onto baking sheet and set aside.
Slice crescent sheet in half widthwise, and then into long, thin strips. Wrap a piece of dough around meatballs to resemble a mummy, leaving a space to make eyes later on.
Bake until meatballs are cooked through and dough is golden, about 15 minutes. Cover sheet with foil if dough starts to get too dark.
Make two mustard dots for eyes on each mummy meatball and serve.