Preheat oven to 375 degrees Fahrenheit.
Spray 9x13 glass casserole dish with oil (I like avocado oil). Place de-stemmed mushrooms gills up in dish. Leave space between mushrooms.
Place meatballs between mushrooms. It’s ok if meatballs are frozen.
Place chopped tomatoes over mushrooms and meatballs. Make sure to get some tomatoes in the mushroom cups. Add more tomatoes if you need to use up the bounty from your garden.
Cook for 30-35 min until meatballs are warm. You should be smelling the mushrooms too.
Remove dish from oven and add cheese. Cook for 5 more minutes until cheese is melted.
When tomatoes aren’t in season use marinara sauce. I use about ½ jar of sauce.