Pre heat oven to 400 and line a baking sheet with parchment.
In a medium dish add the rice crumbs, grated Parmesan and milk. Stir to incorporate and let rest 10 minutes.
Meanwhile place hamburger in another medium dish.
Start to prep the remaining ingredients, which will first get mixed into the milk and crumb mixture (after the 10-minute rest) and then into the beef.)
The easiest way for us to form the same sized meatballs is with a cookie scoop. Use the size you prefer.
Place all meatballs on parchment lined sheet and cook for 20 minutes.
Remove from oven and when cool enough to handle, place on paper towel lined dish.
When completely cool they may be stored in the refrigerator (or frozen) in a Zip Lock bag until ready to use.
Make Marina or warm pre purchased.
The meatballs can be served family style or individually.
Place meatballs in an oven proof dish, top with marinara and slices of fresh mozzarella. Broil until cheese melts, gets a bit of color and sauce is bubbling.
Meanwhile, broil, or grill hoagie or hotdogs style buns, making sure to keep one side intact. We use a brush with a splash of olive oil once cooked or during cooking as you prefer.
Add meatballs and sauce to the bun and enjoy!