This is one of my families favorite pasta dishes. It is a great "make ahead" and freeze meal also by cooking in individual serving dishes. Each shell is filled with yummy goodness that is just delicious.
Bring a pot of water to a boil, add a good pinch of salt and the shells and cook according to pkg. directions. Drain, rinse to cool, and set aside. Meanwhile, brown the ground beef in a skillet, drain the grease, stir in the onion and cook for 5-6 minutes till tender, stir in the garlic and spinach. Cook until spinach has wilted and add in all but 1 C. of the pasta sauce. Remove from heat.
In a bowl, stir together the ricotta, cottage cheese, egg and parmesan cheese.
Spread the remaining cup of pasta sauce in the bottom of a casserole dish. Take each shell and fill with 1 T. of the ricotta mixture, then a good spoonful of the meat mixture, place in the casserole dish, repeat with remaining shells. Top with the mozzarella cheese and bake uncovered at 375 degrees for 25-30 minutes or until the cheese is golden brown and bubbly. 3 stuffed shells per serving.