Delicious Meatball Sub Recipe

Meatball Sub a great Lunch or Dinner. Ingredients: 1 lb. Minced Beef, 1 Egg, 2 Burger Buns (any white Roll or Bread), 1/4 cup milk (lukewarm), 1 tsp Salt, 1/2 tsp Italian Seasoning, 1/2 tsp Paprika, 1/2 tsp Pepper, 1 onion (diced), 2 Garlic Clove (minced), 2 tbsp Parsley (chopped), 1/2 tsp Mustard, 4 tbsp Butter, 3 French Sandwich Rolls, 24 oz. Marinara Sauce, 6 oz. Mozzarella Cheese (shredded)