1. Make the pasta dough and let it rest as directed. Spread a clean tablecloth on a large work surface and dust with the semolina. This is where you will put the pasta once it is shaped.
2. Pinch off a piece of dough about the size of a golf ball and rewrap the remaining dough. Place the piece of dough on a work surface lightly dusted with semolina, and roll it into a rope about the thickness of a finger or fat breadstick. Cut the rope crosswise into marble-sized pieces. Working with one piece at a time, roll each piece into a thin strand 4 to 5 in/10 to 12 cm long and about the thickness of a skinny green bean. As you shape each strand, transfer it to the semolina-dusted cloth. Continue to shape the codette until you have used up all the dough.
(If you are serving the codette the same day, you can leave them out on the cloth for up to a couple of hours.)
3. Bring a large pot of water to a rolling boil and salt generously.
4. While the water is heating, warm 2 tbsp of the olive oil in a large frying pan placed over medium-low heat. Remove the sausages from their casings and pick them apart over the frying pan, allowing the chunks of sausage to drop directly into the pan. Sauté, using a wooden spoon or silicone spatula to break up the large pieces of sausage, for 5 to 7 minutes, or until no trace of pink remains and the meat is cooked throughout. The sausage should still be moist and only very lightly browned. Add the tomato sauce, peas, and the remaining 2 tbsp oil, raise the heat to medium, and cook, stirring occasionally, for 3 to 5 minutes, or until the peas are just tender. Season with salt and pepper. Remove from the heat and cover to keep warm.
5. Carefully drop the codette into the boiling water and stir to separate the noodles. Cover the pot until the water returns to a boil, then uncover and cook until the pasta is al dente. This will take anywhere from 20 to 25 minutes because of the thickness of the noodles. Drain the pasta in a colander set in the sink, reserving about 1 cup/240 ml of the cooking water.
6. Transfer the pasta to the frying pan and gently toss the pasta and sauce to combine thoroughly, adding a splash or two of the cooking water if necessary to loosen the sauce. Transfer the dressed pasta to a warmed serving bowl or shallow individual bowls and shower with a generous amount of cheese. Serve immediately.
Simplify: The codette may be made in advance and frozen (uncooked). Place them, in a single layer and not touching, on semolina-dusted baking sheets/trays, put them in the freezer, and freeze for 1 hour, or until firm. Transfer them a zipper-lock freezer bag or tightly lidded container and freeze for up to 1 month. Because of their thickness, codette must be cooked when they are still “fresh.” If you let them dry, they will not cook properly (see headnote). Freezing them soon after you shape them works beautifully and allows you to do the labor-intensive part of this recipe well in advance.
Cook’s Note: Freshly harvested peas are a sweet and delicate treat. But that sweetness does not last; the longer peas sit after being picked, the starchier they become. If you are buying peas from a farmers’ market or grocery store, check to see when they were harvested. Peas are at their best when used within a few hours of being picked. Look for pods that are full but not bulging; overly mature peas are tough and starchy and not nearly as sweet as smaller ones. If you buy peas in the morning and don’t plan on cooking them until evening, leave them in their pods and store them in the refrigerator; this will help retain their sugar and flavor. You will end up with about 1 cup/140 g shelled peas from 1 lb/455 g peas in the pod. If you are unable to find freshly harvested peas, substitute good-quality frozen peas. In this recipe, add the peas with thawing them first.
Excerpted from The Glorious Pasta of Italy by Domenica Marchetti
"Often you find that there are ways you can improve techniques or recipes," says J. Kenji López-Alt, author of The Food Lab: Better Home Cooking Through Science.