Preheat oven to 350?. Grease a 12 count muffin tin and set aside.
In a mixing bowl, mix together all ingredients, except tomato sauce and mozzarella.
Using a cookie scoop or spoon, add meatloaf mixture to every muffin tin, packing each one as much as you can (they will not rise).
Bake for 23 minutes. Remove from oven, top with sauce and a slice of mozzarella and broil on high for remaining 7 minutes. Be sure to check internal temperature (165?) to make sure they are fully cooked.