Cook pasta shells according to package direction (undercook by 1-2 minutes), drain.
Saute chopped onion in a little olive oil, add in crushed garlic.
When onion/garlic are tender and translucent, add in a bag of fresh spinach (chopped). Cook until spinach is wilted.
In a large bowl combine ricotta, parmesan, 1/2 c. grated mozzarella, egg, nutmeg, salt & pepper. Mix until well combined.
Add spinach mixture to cheese mixture and combine.
Pour a little pasta sauce in bottom of casserole dish (I made two 9x11' pans).
Gently stuff the pasta shells with cheese mixture and place open side up in saucy pan.
Top with more sauce, some grated mozzarella cheese, and a sprinkle of parmesan. Cover with foil.
Heat in 350* oven until hot and bubbly (approx. 35-45 minutes)
**makes 2 casseroles. Enjoy one tonight and freeze the other.