Preheat your oven to 400°F (200°C).

In a large bowl, combine milk and breadcrumbs. Let sit for 5 minutes to create a panade.

Add ground beef, egg, onion, garlic, Italian seasoning, salt, and pepper to the bowl. Mix gently until just combined – don't overmix!

Form mixture into 18-24 meatballs (about 1.5 inches each).

Place meatballs on a lined baking sheet and bake for 15-20 minutes, or until cooked through.

Meanwhile, warm BBQ sauce in a large skillet over medium heat.

Transfer cooked meatballs to the skillet and coat with sauce.

Toast sub rolls under the broiler for 1-2 minutes.

Place 3-4 meatballs in each roll, top with cheese, and broil until cheese melts.

Garnish with optional toppings and serve hot.