Stuffed Shells with Sausage, Cheese and Spinach

I have been craving stuffed shells for some time now and found this recipe (a tweak of Giada's Turkey and Artichoke Stuffed Shells with Arrabbiata) to be very easy!

Ingredients:
1 (12-ounce) box jumbo pasta shells (recommended: Barilla)
3 tablespoons extra-virgin olive oil
1/2 large yellow onion, chopped (about 1 cup)
3 cloves garlic, chopped
1 pound hot sausage - i used a mix of hot and mild
1/2 teaspoon kosher salt, plus 1/2 teaspoon
1/4 teaspoon freshly ground black pepper, plus 1/4 teaspoon
1 (15-ounce) container full fat ricotta cheese
3/4 cup grated Parmesan
2 eggs, lightly beaten
1/4 cup chopped fresh basil leaves
2 tablespoons chopped fresh flat-leaf parsley
2 cups of fresh chopped spinach
1 1/2 cups grated mozzarella (about 5 ounces)


Inredients for Sauce:
2 large cans of marinara sauce
Panchetta
2 teaspoons crushed red pepper flakes

4 garlic cloves, minced
Italian Seasonings (Basil, Thyme, Oregano)

Directions for sauce:
Heat the olive oil in a large soup pot over medium heat. Add the pancetta and saute until golden brown, about 5 minutes. Add the garlic and saute until tender, about 1 minute. Add the marinara sauce and red pepper flakes, italian seasonings, salt and pepper and bring to a simmer. Remove from heat and let cool until ready to use.

Directions for Stuffed Shells
Bring a large pot of salted water to a boil over high heat. Add the pasta and partially cook until tender but still very firm to the bite, stirring occasionally, about 4 to 5 minutes. Drain pasta.

Meanwhile, in a large heavy skillet, heat the olive oil over medium-high heat. Add the onions and the garlic and cook until the onions are soft and starting to brown, about 3 minutes. Add the sausage, 1/2 teaspoon salt, and 1/4 teaspoon black pepper and continue to cook, stirring occasionally, until the meat is slightly golden and cooked through. Add the chopped spinach and stir to combine. Remove from heat and let cool.

In a large bowl combine the cooled sausage mixture with the ricotta cheese, Parmesan cheese, eggs, basil, parsley, and the remaining salt and pepper. Stir to combine.

To stuff the shells, cover the bottom of a 9 by 13 by 2-inch baking dish with 1 cup of prepared marinara sauce. Take a shell in the palm of your hand and stuff it with a large spoonful of turkey mixture, about 2 tablespoons. Place the stuffed shell in the baking dish. Continue filling the shells until the baking dish is full. Drizzle the remaining Marinara Sauce over the shells, top with the grated or sliced mozzarella. If freezing, cover tightly with plastic wrap and place in the freezer for 1 day and up to 1 month.

To bake, preheat the oven to 400 degrees F. Bake until the shells are warmed through and the cheese is beginning to brown, about 60 minutes (20 minutes if shells are unfrozen.)