One Pot Meaty Shells and Cheese

1 pound lean ground beef
1 medium onion, chopped
2 cloves garlic, minced
2 tablespoons olive oil
1 carton (33.5 ounce) or equivalent canned tomato sauce, with 3/4 to 1 cup water to rinse the container and add to the pot
2 cups mini shells
1 1/2 tablespoons chopped fresh parsley
1/2 tablespoon dried Italian seasoning
salt and pepper to taste
2 cups shredded mozzarella cheese
1/4 cup grated Parmesan cheese

Heat oil in a large skillet, and brown the ground beef with the onion. Drain excess fat, add the minced garlic, tomato sauce, water, parsley, Italian seasoning, and salt and pepper. Stir in the mini shells, cover and simmer over medium-low heat for 15-20 minutes, stirring often, until the shells are tender.

Stir in the shredded mozzarella and Parmesan cheese, and serve immediately.