Gather ingredients: ground meat (beef, pork, veal, or turkey), breadcrumbs, grated Parmesan (optional), minced garlic, chopped onion (optional), egg, milk or water, salt, black pepper, dried oregano or Italian seasoning, olive oil (for browning, optional)
Preheat oven to 400°F (205°C) or heat a skillet over medium heat
In a bowl, mix breadcrumbs and milk (let sit 2–5 minutes)
Add meat, egg, garlic, onion (if using), Parmesan (if using), salt, pepper, and seasonings
Mix gently until just combined (avoid overmixing)
Shape into meatballs (about 1 to 1.5 inches / 2.5 to 4 cm)
Optional browning: heat olive oil in a skillet and brown meatballs on all sides, 2–4 minutes total
Oven method: place meatballs on a lined baking sheet and bake 15–22 minutes, until cooked through
Stovetop method: simmer meatballs in sauce on low to medium-low for 20–30 minutes, turning occasionally
Check doneness: internal temperature 160°F (71°C) for beef/pork/veal; 165°F (74°C) for poultry
Serve with marinara sauce, pasta, or in a sandwich