Bring a large pot of generously salted water to boiling. Cook linguine according to package directions. Drain, reserving 1/2 cup cooking liquid. Return to pot, cover to keep warm.
Meanwhile, for pan sauce, cut sausage in little blunt-edge meatballs. In a large skillet cook sausage over medium-high heat about 5 minutes, until golden brown all over, adding garlic during last minute of cooking time. Set aside sausage.
In a medium bowl whisk together the egg yolks, milk, 1/2 cup grated cheese, the lemon peel, salt, and pepper. Add to the pot with the pasta. Add the hot sausage and chopped greens. Toss all ingredients together, letting heat from pot and linguine cook and thicken egg to a silky sauce. Add 1/4 to 1/2 reserved pasta water to loosen. Toss with the parsley and shaved cheese. Serve immediately in shallow bowls and plates. Makes 4 servings.