The sauce recipe is linked in the ingredients list above. Make it and let it cool slightly while you prepare everything else. If using a large braising dish like we have pictured here, you could make the sauce then add the stuffed pasta to the same dish to bake.
1 recipe of spicy sausage sauce
Bring a large pot of salted water (about 2 tablespoon per 6 qts of water) to a boil. Add the shells to the boiling water and cook for 70% of the cooking time indicated on the package. Gently remove the shells to an ice bath of cold water to stop the cooking and cool down. They can sit in the ice bath for up to 15 minutes, then remove them to a towel to dry before stuffing. The shells will fully cook to al dente in the oven once stuffed.
1 pound dried jumbo pasta shells
In a large bowl, combine all of the filling ingredients and mix with a gloved hand or a large fork to ensure the filling is well combined. The filling can be transferred to a piping bag if desired to make stuffing the shells easier.
5 ounces spinach, 16 ounces ricotta cheese, 7 ounces grated asiago cheese, 4 ounces grated parmesan cheese, 10 basil leaves, Pinch ground nutmeg, Pinch kosher salt, ½ teaspoon ground black pepper, 1 large whole egg
Preheat the oven to 350°F. Using a piping bag or simply a spoon and your fingers, stuff shells completely with the creamy ricotta filling, being careful not to split the pasta. Put a thin layer of the sauce on the bottom of the baking dish, then assemble the shells in the dish. They can be as close together as you need to fit them in the dish. Cover the stuffed pasta shells with the remaining sauce and sprinkle with a little parmesan cheese on top.
Additional Parmesan cheese to sprinkle on top before baking
Place the dish in the oven uncovered and bake for 40 minutes or until the sauce is bubbling around the sides of the dish. Remove and serve. Garnish with fresh basil, more Parmesan cheese, and extra crushed red pepper flakes at the dinner table if desired.