Smashed Meatball Subs

In a large bowl, combine the finely chopped onion, egg, half-and-half, grated Parmesan cheese, and breadcrumbs. Mix well.

Add the ground beef to the bowl. Season directly on top of the meat with salt, pepper, and garlic powder.

Using your hands, gently mix all the ingredients together until just combined. Do not overmix.

Spread the meatball mixture evenly onto the cut side of each split sub roll.

Heat olive oil on a griddle or in a large skillet over medium-high heat.

Place the sub rolls meat-side down onto the hot griddle. Press down gently to ensure good contact.

Cook for 3-4 minutes, until the meat is browned and cooked through.

Flip the subs and place them on a baking sheet, cooked meat-side up.

Spread a layer of marinara sauce over the cooked meat, then top generously with shredded mozzarella cheese.

Place the baking sheet under the broiler for 1-2 minutes, or until the cheese is melted, bubbly, and lightly browned.

Remove from the oven. You can fold the halves together to create a sandwich or serve open-faced. Slice and enjoy immediately.