01 -
Set the oven temperature to 375°F and position the rack in the middle.
02 -
Lightly grease a 9x13 inch casserole dish using cooking spray and place frozen meatballs in an even layer.
03 -
Bake the meatballs for 20 minutes.
04 -
Remove casserole from oven, pour marinara sauce over meatballs and gently stir to combine. Spread evenly, then sprinkle shredded mozzarella on top.
05 -
Return to oven and bake for an additional 15 to 20 minutes until hot and bubbly, ensuring the internal temperature reaches 160°F. Optional: broil the cheese briefly to brown.