Preheat oven to 375 degrees F and coat a 9×13 inch baking dish with cooking spray. Set aside.

Cook the shells in a large pot of salted boiling water according to box instructions or until al dente, about 11 minutes. Drain and lightly coat in olive oil or cooking spray to prevent the shells from sticking together.

In a large frying or sauté pan, heat olive oil and garlic and cook until garlic is fragrant, about 1 minute. Add spinach and sauté until wilted, about 3 minutes. Remove from the pan and drain excess liquid. Let spinach cool for a few minutes and then chop.

Pour the marinara sauce into the bottom of a 13x9 inch baking dish, set aside.

In a large bowl combine spinach, ricotta, cheeses, Italian seasoning, egg, salt and pepper. Mix until combined.

Stuff each shell with the filling of about 2 heaping tablespoons in each shell and place in the dish. Top with more shredded mozzarella cheese (optional).

Cover with foil and bake for 20 minutes, then remove foil and bake for 5 more minutes. Garnish with parsley and enjoy!