How to Make It
In a large pot of boiling salted water, cook the farfalle until al dente; about 1 minute before the farfalle is done, add the shredded zucchini to the pot. Drain the farfalle and zucchini, reserving 1/4 cup of the pasta cooking water.
Meanwhile, in a large, deep skillet, melt the butter. Remove from the heat. Stir in the Greek yogurt and the 1 cup of grated Parmigiano-Reggiano and season the yogurt sauce with freshly grated nutmeg, salt and pepper.
Add the farfalle, zucchini and reserved pasta water to the saucepan and cook over low heat, tossing, until the sauce coats the pasta; transfer to warmed bowls and serve with the extra cheese.