- 3 tablespoons milk
- 1 large egg, beaten
- ½ cup grated Parmesan cheese, plus more for topping
- ¼ cup seasoned bread crumbs
- 1 1/2 tablespoons chopped fresh oregano leaves
- 1 teaspoon kosher salt
- ½ teaspoon cracked black pepper
- ½ pound ground chuck
- ½ pound ground pork
- 4 cups marinara sauce, store bought or homemade
- 1/4 cup extra-virgin olive oil
- 1 large yellow onion, finely chopped
- 3 garlic cloves, minced
- 1 (28-ounce) can crushed tomatoes
- 1 (28-ounce) can San Marzano whole plum tomatoes
- ¼ cup chopped fresh basil
- Kosher salt and cracked black pepper
- 6 hero rolls, split
- 6 ounces mozzarella cheese, grated (about 1 ½ cups)
- ½ cup grated Parmesan cheese
- ½ cup fresh basil, torn
- For the meatballs, preheat the oven to 400º F. Line a rimmed baking sheet with parchment paper.
- In a large bowl, combine the milk, egg, cheese, bread crumbs, oregano, salt, and pepper. Add the ground meats and mix gently to avoid overworking the meat. Shape into small golf ball-sized meatballs, and put them on the prepared baking sheet. You should have 18 to 24 meatballs.
- Bake the meatballs until they are cooked through and lightly browned on all sides, 15 minutes.
- For the sauce, in a large saucepan set over medium heat, heat the olive oil. Add the onion and garlic and cook until soft and starting to brown, 3 to 5 minutes. Add the tomatoes and their juices, breaking them up with the back of a wooden spoon, and bring to a boil, stirring often. Lower the heat to medium-low and simmer until the sauce has thickened, 15 to 20 minutes. Stir in the basil and season with salt and pepper. At this point, the tomato sauce will keep in an airtight container in the refrigerator for 1 week, and up to 6 months in the freezer.
- Put the meatballs in the simmering sauce. Gently toss to coat and cook for 5 minutes.
- For the sandwiches, put the rolls on baking sheet, cut side up. Put 3 to 4 meatballs on each roll, spoon some of the sauce over the meatballs, and top with the cheeses.
- Bake until cheese melts, 3 to 5 minutes. Top with fresh basil and serve.