Step 1

Preheat oven to 400 degrees. Spray a rimmed baking sheet with non-stick spray.

Step 2

Add the ground beef, pork, bread crumbs, Parmesan, parsley, garlic, onion, and egg to a large mixing bowl and combine well with your hands. Do not overmix.

Step 3

Separate the mixture into 12 equal sized chunks and roll into meatballs.

Step 4

Place meatballs on prepared baking sheet and bake for 10 minutes.

Step 5

Add all of the sauce ingredients to a 6 quart slow cooker and stir well to combine.

Step 6

Remove the meatballs from the oven and place in the slow cooker with the sauce.

Step 7

Cover and cook on low for 4 hours.

Step 8

Open the hoagie rolls and butter the insides of each roll.

Step 9

Sprinkle evenly with the garlic salt, about ½ teaspoon per roll or to taste.

Step 10

Place opened hoagie rolls on a large baking sheet under the broiler and broil until as toasted as you’d like. Keep a close eye on the bread as it will go from toasted to burnt very quickly.

Step 11

Remove the bread from the oven and add meatballs to the bread. Top with a spoonful of sauce.

Step 12

Top each sandwich with 2 slices of fresh mozzarella and a sprinkling of parsley.

Step 13

Return to the broiler for 1 minute to let the cheese soften.

Step 14

Serve immediately.