Mix ground meat (beef, pork, turkey, or a blend) with breadcrumbs, grated onion or onion powder, minced garlic, egg, salt, pepper, and Italian seasoning
Add chopped parsley (optional) and a splash of milk or water (optional) to keep the mixture tender
Form into evenly sized meatballs (about 1 to 1.5 inches / 2.5 to 4 cm)
Preheat oven to 400°F (205°C) or heat a skillet over medium heat
For oven cooking: place meatballs on a lined baking sheet and bake 15–22 minutes, until cooked through (internal temp 160°F / 71°C for beef/pork; 165°F / 74°C for poultry)
For pan cooking: brown meatballs in a little oil, turning to sear on multiple sides, then reduce heat and cook until cooked through (add a splash of water or sauce if needed)
For simmering in sauce: brown first (optional), then simmer in marinara for 15–25 minutes until cooked through
Rest meatballs 3–5 minutes before serving
Serve with pasta, sauce, or sub sandwiches