Preheat oven to 400 degrees.

In a large bowl, combine beef, egg, olive oil, 6 ounces mozzarella, garlic, basil, parsley, panko, bacon pieces, and salt & pepper.

Form meat into 12 meatballs by rolling into a round ball, then flattening to wrap one of the cubed cheeses around it.

Arrange meatballs in a 9×13 glass baking dish. Pour tomato sauce over meatballs.

Bake for 30 minutes.

When 5 minutes remain, sprinkle with remaining mozzarella. Serve on slider buns.