Place egg yolks, cream, lemon zest, garlic and cheese in a large bowl and whisk. When pasta is al dente, reserve 1/2 cup pasta water in a small cup and strain pasta in colander (do not rinse). Place pasta in the bowl with cream/egg mixture. Toss well. If sauce is too thick add a little pasta water to thin. (You may need a little, you may need a lot, you may need none at all) Salt and pepper to taste. Add sausage and rocket (arugula) and toss. Serve immediately.