One of my favorite sandwiches is the warm, sloppy, melty, meatball sub (sometimes called a hoagie). It’s Italian-American comfort food at it’s finest with beef meatballs slathered in sauce and broiled until the mozzarella cheese topping melts and oozes down the sides of the meatballs.
Add the beef, pork, eggs, breadcrumbs, milk, Parmesan, parsley, oregano, Calabrian chilies, crushed red pepper, salt and pepper to the mixing bowl. Gently combine the mixture with your hands until all ingredients are just incorporated.
Roll the mixture into 1½-ounce balls (about 1½-inches in diameter) and place on a parchment-paper-lined baking sheet. Bake until golden brown and cooked through, about 20 minutes.
Set meatballs aside until ready to assemble the sandwiches.
Preheat oven to broil.
Working one at a time, spoon ¼ cup sauce into the roll then add three meatballs. Spoon another ¼ to 1/3 cup of sauce over the top and alternate slices of the mozzarella and provolone over the top of the meatballs. Repeat with the remaining rolls and ingredients.
Broil until the cheese is bubbly and the bread is golden brown, about 2 minutes. Serve immediately.