Soak the breadcrumbs: In a bowl, combine breadcrumbs and milk. Let sit 5 minutes until the mixture becomes a soft paste.

Build the flavor base: Add eggs, Parmesan, garlic, parsley, grated onion, salt, pepper, oregano, and red pepper flakes to the breadcrumb mixture. Stir until combined.

Mix in the meat: Add ground beef and pork. Use your hands to gently fold everything together until just combined. Do not overmix or the meatballs will be tough.

Shape the meatballs: Scoop into 1.5-inch balls (about 2 tbsp each). Lightly oil your hands for smoother shaping. You should get 24–28 meatballs.

Choose your cooking method: Stovetop sear + simmer: Heat 2 tbsp olive oil in a large skillet over medium-high. Sear meatballs in batches until browned on two sides, 3–4 minutes total. Add marinara, reduce heat, and simmer 15–20 minutes until cooked through.

Oven-baked: Heat oven to 425°F (220°C). Place meatballs on an oiled, rimmed baking sheet. Bake 12–15 minutes, until just cooked. Simmer in warmed marinara 5–10 minutes for best flavor.

Air fryer: Heat to 390°F (200°C). Cook meatballs in a single layer for 8–10 minutes, shaking halfway. Finish in sauce if desired.

Taste and adjust: Spoon a bit of sauce, taste, and adjust salt, pepper, or a pinch of sugar if the tomatoes are too acidic.

Serve your way: Toss with spaghetti, pile on a toasted roll with mozzarella, or spoon over polenta. Garnish with parsley and extra Parmesan.