This was a really fun dish to make. One of the reasons that it was so fun was because my good friend Stacy and I made it together for a dinner with our husbands. We both wanted to try something new and this recipe seemed perfect for us. The recipe was so large that we had to use two dishes: one 9x13" and one 8x8". This actually worked really well because we tried a little experiment. We followed the recipe below for the bigger dish and then used pasta sauce and mozzarella in the smaller dish. Both dishes turned out really well, except that if you decide to take the pasta sauce/mozzarella route, bake the dish at 350 degrees. The sauce burned a little bit at the edges on 375.
Source: Annie's Eats, adapted from Simply Recipes
1 12-oz. package jumbo pasta shells
1 tbsp. olive oil
1 cup yellow onion, finely chopped
1 lb. Italian sausage, casings removed
3 cloves garlic, minced
1 large egg, lightly beaten
1 15-oz. container ricotta cheese
6-7 oz. fresh spinach, chopped OR 10 oz. frozen chopped spinach, thawed and drained
1 cup freshly grated Parmesan cheese, divided
1 tbsp. chopped fresh basil or 1 tsp. dried basil
1/4 cup bread crumbs
1/2 tsp. salt
1/2 tsp. pepper
1 28-oz. can chopped tomatoes with herbs, including the liquid
Bring a large pot of salted water to boil. Cook pasta shells according to package directions. Drain, rinse with cold water, and set aside.
Heat olive oil in a large skillet over medium-high heat. Add the onions and cook until softened, about 5 minutes. Add the sausage to the pan, breaking it into smaller pieces as it cooks. Cook until the sausage is completely cooked through and no pink remains, about 5 minutes. Add the garlic and cook until fragrant, about 30 seconds. Remove from the heat.
In a large mixing bowl, combine the egg, ricotta, spinach, 1/2 cup of the Parmesan, basil, bread crumbs, salt, and pepper. Stir together to combine. Add the cooked sausage mixture to the bowl and stir until evenly mixed.
Preheat the oven to 375 degrees F. Spread a thin layer of the chopped tomatoes in the baking dishes (either three 8×8″ pans, or one 9×13″ and one 8×8″). Stuff each shell with some of the sausage and cheese mixture, and arrange in the baking dishes, open side up. Spread the remaining tomatoes over the top of the pasta shells.
Cover the pans with foil and bake for 30 minutes, until hot and bubbling. Remove foil and sprinkle with remaining Parmesan cheese. Bake, uncovered, for 10 more minutes.