Make the panade. In a large bowl, combine bread crumbs and milk. Let it sit for 2–3 minutes until the crumbs absorb the liquid and form a paste.

Mix the meatballs. Add ground meat, egg, Parmesan, onion, garlic, parsley (or Italian herbs), salt, pepper, and red pepper flakes. Gently mix with your hands or a fork until just combined. Don’t overmix or the meatballs will get dense.

Shape the meatballs. Form 16–20 golf ball–sized meatballs. Keep them similar in size so they cook evenly.

Brown the meatballs. Heat olive oil in a large skillet over medium-high. Brown meatballs in batches, turning to get color on multiple sides, about 5–7 minutes total. They don’t need to be cooked through yet.

Simmer in sauce. Pour marinara into the skillet with the browned meatballs. Reduce heat to medium-low, cover partially, and simmer 12–15 minutes until meatballs are cooked through and tender. Taste sauce and adjust salt if needed.

Toast the rolls. Preheat the broiler. Split the rolls (keeping one long side connected), brush with melted butter, and sprinkle with a pinch of garlic powder if using. Broil cut-side up 1–2 minutes until lightly toasted. Watch closely to prevent burning.

Assemble the subs. Lay a slice of cheese in each roll. Spoon in 3–4 meatballs with plenty of sauce. Top with another slice of cheese.

Melt the cheese. Return the assembled subs to the broiler for 1–2 minutes until the cheese is bubbly and melted. Garnish with chopped basil or parsley if you like.

Serve hot. Add extra sauce on the side. A quick green salad or potato chips round out the meal.