How to Make It
Bring 3 quarts of water to a boil and add 1 tablespoon of salt. Set up an ice bath nearby. Submerge the peas into the boiling water and cook until tender yet still bright green, 1-2 minutes. Remove the peas with a slotted spoon, reserving the boiling water, and plunge them into the ice bath to cool. Once the peas have cooled, remove them from the ice bath and allow to dry on a plate lined with paper towels. Using the same water, blanch the mint leaves for just 10-15 seconds. Transfer immediately to the ice bath. Drain well.
In the bowl of a food processor, combine the peas, mint, Parmigiano-Reggiano and heavy cream. Season with salt and pepper and pulse to form a smooth paste.
Using a pasta machine, roll out the pasta dough on the thinnest setting and then cut the pasta sheets into 3-inch squares. Place 1 tablespoon of the pea filling on each square and fold over to form rectangles. Continue filling and shaping until all the pasta and filling are used. Cover and refrigerate until needed or place on baking sheets between layers of dish towels and freeze overnight. The next day, place in freezer bags and store up to 1 week.
In a medium saucepan, bring the tomato sauce to a boil. Add the sausage, reduce the heat to a simmer, and cook for 1 hour, skimming off the fat as it is rendered from the meat. Remove the sauce from the heat, cool briefly, and pulse it in a food processor until smooth. Transfer to a 12-inch skillet and keep warm.
Bring 6 quarts of water to a boil and add 2 tablespoons of salt.
Cook the pasta in the boiling water until tender, 2 to 3 minutes. Drain the pasta and add to the pan with the sauce. Toss gently over high heat for 1 minute. Add the reserved mint leaves, toss 1 minute more, then divide evenly among eight warmed dinner plates. Grate the Grana Padano over each plate and serve immediately.