Cook Italian sausage. Wipe out pan when finished and use same pan for spinach.
1 pound Italian Sausage
Sautee garlic for a few seconds in a pan. Add fresh spinach. I add in large batches, allowing spinach to cook down before adding more. Keep all spinach in pan until it has all been cooked. Remove spinach to a colander and allow spinach to cool. Once cool, squeeze out all liquid. This takes a lot of squeezing. Keep rotating spinach in your hands and squeeze until all liquid is removed.
Add cooled sausage, be careful to not add any of the grease.
Carefully stuff each pasta shell with 3 tablespoons of cheese filling. Place each stuffed shell in a greased baking dish with a layer of marinara sauce. Continue filling all shells until dish is full.
3 cups Marinara Sauce
Drop spoonfuls of sauce around the filled shells. Place diced mozzarella on top of shells. Sprinkle remaining parmesan cheese over top
4 ounces Fresh Mozzarella, ¼ cup Parmesan Cheese
Cover dish with foil and bake at 375 for 30 minutes. Remove foil and continue cooking for an additional 20 minutes. Turn broiler on for an additional 5 minutes and cook until the cheese is slightly browned.
Remove from oven and allow dish to rest for 10 minutes Garnish with fresh herbs and serve with additional marinara sauce
1 teaspoon fresh herbs
Notes
I usually cook a few extra shells in case one falls apart and can't be used
The spinach cooks down from about 10 cups of spinach to about 1 cup of cooked and squeezed spinach
To make ahead of time, cover and refrigerate after filling shells and adding sauce and cheese. Bake as directed, increasing baking time by 15-20 minutes.
To prevent cheese from sticking to foil, spray foil lightly with a nonstick spray before placing on dish
Substitutions and variations
Use frozen spinach in place of fresh. Allow spinach to fully thaw and then squeeze out all liquid
Omit Italian sausage to make a vegetarian version
Use cottage cheese in place of the ricotta cheese. This is a great way to save money when making this dish. The cottage cheese is extra creamy and once cooked, you can't tell the difference.