Mini Meatball Subs

1 pound ground beef
1/2 cup chopped onion
1/2 cup chopped green pepper
1/2 cup crushed butter-flavored crackers
1 egg
1 teaspoon Worcestershire sauce
1 teaspoon chopped garlic
1 teaspoon seasoned salt
1 teaspoon ground black pepper
1 (26.5 ounce) can spaghetti sauce
1/2 cup shredded mozzarella cheese
1/3 cup grated Parmesan cheese
8 dinner rolls, split

Preheat an oven to 350 degrees F (175 degrees C).
Combine ground beef, onion, green pepper, crackers, and egg in a large bowl. Season with Worcestershire sauce, garlic, seasoned salt, and pepper; mix well. Form mixture into 8 meatballs. Place meatballs in a 9x13 inch baking dish.
Bake meatballs in the preheated oven for 20 minutes. Pour the spaghetti sauce into a large saucepan; bring to a simmer over low heat. Stir baked meatballs into the simmering sauce. Do not turn oven off. Simmer sauce until meatballs are fully cooked, about 20 minutes.
Place one meatball, a sprinkle of mozzarella, a sprinkle of Parmesan, and a bit of sauce between each roll. Place sandwiches in hot oven; bake until cheeses melt, about 7 minutes.