Soak the breadcrumbs: In a mixing bowl, stir the breadcrumbs with the milk and let sit for 3–4 minutes until softened.
Build the mixture: Add the ground beef, egg, grated onion, garlic, Parmesan, parsley, red pepper flakes, smoked paprika, oregano, salt, and black pepper. Mix gently with your hands until just combined.
Don’t overwork it.
Shape the meatballs: Form into golf ball–sized balls, about 1.5 inches. You should get 18–22 meatballs. Keep them uniform so they cook evenly.
Brown the meatballs: Heat olive oil in a large skillet over medium-high.
Sear the meatballs in batches, turning to brown on all sides, about 5–7 minutes total. They don’t need to be fully cooked yet. Transfer to a plate.
Simmer in marinara: Pour marinara into the skillet (drain excess fat if needed).
Add a splash of red wine if you like. Nestle the meatballs into the sauce, cover partially, and simmer over medium-low for 15–20 minutes, until cooked through and tender.
Taste and adjust: Add a pinch of sugar if the sauce is too tangy, more red pepper if you want extra heat, and a handful of torn basil if you have it.
Serve: Spoon over hot pasta, tuck into toasted sub rolls with mozzarella, or serve with creamy polenta or roasted vegetables. Finish with extra Parmesan and parsley.
Alternate oven method: Bake shaped meatballs on a lined sheet at 425°F (220°C) for 12–15 minutes, then simmer in marinara for 10 minutes to absorb flavor.