3 TBS warm water (preferably the pasta cooking water).
grated pecorino cheese, for serving
Add the fava beans, mint, mascarpone, and ricotta to a food processor. Process until smooth and fluffy. Season to taste with sea salt. Transfer to a bowl, cover, and refrigerate.
Use a pasta machine to roll out the pasta dough in thin sheets. Target the third or fourth thinnest setting as your ultimate thickness of the pasta.
Lay the pasta sheets flat on a lightly floured surface, covering the sheets you aren’t using with a piece of plastic wrap. Use a knife to score the pasta sheets into 2 inch squares. Place 2 teaspoons of the chilled filling in the center of half the squares. Wet your finger with water and run it along the edge of each square, then cover the squares with filling with another sheet of the pasta. Press the sheets firmly together around the edges of each filled square, forming ravioli. Use a ravioli cutter or knife to cut the ravioli apart, then firmly press the edges together again to ensure there are no air bubbles. Repeat until you have used all of the pasta dough, re-rolling any dough scraps as needed.
Bring a large pot of salted water to a gentle boil. Gently place the ravioli in the boiling water and cook just until al dente, about 2-3 minutes. They should be floating at the surface of the water when they are ready. Remove them from the water with a slotted spoon and place them on a large plate. Drizzle the ravioli with just a little olive oil to keep them from sticking.
Add the 3 TBS of the pasta cooking water to a small frying pan, and bring to a simmer over low heat. Whisk in the truffle butter one piece at a time, allowing the butter to melt between additions. When you have incorporated all of the truffle butter, add the cooked ravioli to the frying pan and toss gently to coat with the butter sauce. Divide between plates, sprinkle with the grated pecorino, and serve immediately.