Preheat oven to 350 F. Brown the beef, onion & garlic in a skillet. Once completely cooked, drain.
Mix all ingredients together in large bowl, except mozzarella. Then put in casserole dish.
Cook at 350 F covered for 30-35 minutes. Uncover, and cook an additional 20-30 minutes until rice is tender. Remove foil, add mozzarella and cook another 5 minutes until melted.
Notes
TIPS, SUBSTITUTIONS & MORE:Can substitute cream of mushroom soup with dry powder and mixed with 2-1/2 cups milk, in place of the can of soup & water/milk.Add any frozen veggies your family likes, or even a small can of mushrooms. Add more mozzarella if you'd like..you can't go wrong with more cheese!I think this would taste great with chicken instead of beef, too. ***oven times vary, type of casserole dish, etc so check your rice carefully- if may need more or less time to bake.