In a large mixing bowl, combine the ground beef, ground pork, chopped bacon, breadcrumbs, Parmesan cheese, parsley, egg, garlic, salt, black pepper, and smoked paprika. Mix until well combined.
Form the mixture into meatballs, about 1.5 inches in diameter, and place them on a baking sheet lined with parchment paper.
Bake the meatballs in the preheated oven for 20-25 minutes, or until cooked through and browned.
While the meatballs are baking, heat the marinara sauce in a saucepan over medium heat. Once the meatballs are done, add them to the sauce and stir gently to coat.
Slice the hoagie rolls lengthwise, but not all the way through. Place them on a baking sheet.
Spoon the meatball and sauce mixture into each hoagie roll, then top with shredded mozzarella cheese.
Return the loaded hoagie rolls to the oven and bake for an additional 5-10 minutes, or until the cheese is melted and bubbly.
