In a large bowl add the ground beef, egg, onion, bread crumbs, oregano, salt and pepper and stir to combine. Shape into 32 balls and arrange on a rimmed baking sheet. Bake for 25 minutes, uncovered. Remove from oven and discard the fat.
In a 3 1/2 to 4-quart slow cooker, add the crushed tomatoes, red pepper, brown sugar, dijon, chili powder, garlic powder, sriracha, nutmeg and season with salt and pepper. Stir to combine. Add the cooked meatballs, stirring gently to coat.
Cover and cook on low for 3-4 hours.
Place meatballs on toasted hoagie rolls and top with extra sauce and cheese. Serve immediately.
Notes
Tips for Storing
Refrigerator: Store leftover meatballs and sauce in an airtight container for up to 4 days. Keep the rolls separate so they do not get soggy.
Freezer: The meatballs and sauce freeze really well together. Let everything cool completely, then transfer to a freezer-safe container or zip-top bag for up to 3 months.
Reheating: Warm the meatballs and sauce in a saucepan over medium-low heat, stirring occasionally, until heated through. You can also reheat them in the slow cooker on the warm setting for about an hour.
Meal prep tip: The meatballs can be made and baked up to 2 days in advance and stored in the fridge. Just add them to the slow cooker with the sauce when you are ready to cook.
Freeze unbaked meatballs: Shape the meatballs, freeze them on a baking sheet until solid, then transfer to a freezer bag. Thaw overnight in the fridge and bake as directed before adding to the slow cooker.