• Preheat oven to 350°F.

Pasta

• Bring a pot of salted water to boil and cook pasta 4 minutes less than the instructions on the box. (The shells will continue to cook in the oven.) Drain the noodles and let them cool enough to touch.

Filling

• In a medium bowl, combine ricotta cheese, mozzarella cheese, parmesan cheese, romano cheese, cream cheese, garlic, salt, pepper, and basil.
• Add mixture to a piping bag (or a zipped plastic bag).
• Once noodles are cooled, use the piping bag to fill the individual noodles with the filling. Set aside.

Sauce

• In a large saucepan over medium heat, add butter. Once the butter has melted, add onions and cook until translucent and fragrant (about 5 minutes).
• Add garlic and cook 1 more minute.
• Add sun-dried tomatoes, oregano, paprika, salt, and pepper. Stir to combine.
• Add flour and cook 1-2 more minutes. (The mixture will thicken.)
• Add broth, and stir, using a wooden spoon. Scrape the brown bits off the bottom of the pan.
• Add heavy cream, spinach, and parmesan cheese. Continue cooking until the spinach is wilted, or about 3-5 minutes.

Assembly

• To a 12-inch cast-iron (or oven-safe) skillet, add 1 cup of the sauce.
• Top the sauce with an even layer of the stuffed noodles.
• Cover the pasta with the remaining sauce and top with mozzarella cheese. (Make sure the shells are completely coated with the sauce to prevent the pasta from getting crunchy.)
• Bake for 10 minutes. Then, broil the shells for 2-3 minutes (watching carefully), or until the cheese is golden brown and bubbly.
• Serve garnished with fresh basil.