Sausage, Spinach and Mushroom Manicotti

1 1-lb bag spinach, chopped
1 lb mild Italian sausage
Olive oil
1/2 onion chopped
1 tbs chopped garlic
8oz baby bella mushrooms, coarsely chopped
1/2 c chicken broth
1 8oz block cream cheese
1/4 c torn basil leaves
1 cup Parmesan cheese
1 cup mozzarella cheese
1/2 c prepared tomato basil sauce
12 - 14 manicotti shells

In a large skillet lightly coat the bottom with olive oil, heat and then brown the sausage, onion and garlic together for 5 to 6 minutes. Add the mushrooms and continue cooking for another 3 to 4 minutes. Season with salt and pepper, and add the chicken broth, scraping the bottom of the pan. Add the spinach and turn to coat. Cook until the spinach is wilted and the broth has evaporated.
In a large pasta pot, boil the shells in batches and let them cool in a casserole dish.
In a large bowl, cube the cream cheese and add 3/4c Parmesan cheese and the torn basil.
Pour the sausage mixture over the cheese and begin stirring to melt the cheeses and incorporate through.
Move the shells to a plate or board and dry out the casserole dish. Stuff the cheese mixture into the shells and line up in the casserole dish (they will be packed in a standard 9x11 pan.)
Spread any remaining stuffing around the shells in the pan. Top with mozzarella, the tomato sauce and the remaining 1/4 cup of Parmesan.
Bake at 400 for 20 minutes. Let it rest for about 5 minutes and then serve immediately.