Step 1

In a large frying pan, melt 1 tablespoon of the butter with 2 tablespoons of the oil over moderate heat. Add the onions, 1/2 teaspoon of the salt, and the sugar and cook, stirring frequently, until the onions are well browned, about 20 minutes. Remove from the pan.

Step 2

In the same pan, melt the remaining 1 tablespoon butter with 1 tablespoon of the oil over moderate heat. Add the mushrooms and 1/4 teaspoon of the salt and cook, stirring occasionally, until tender and brown, about 8 minutes. Add the reserved onions, the parsley, the remaining 1/4 teaspoon salt, and the pepper.

Step 3

In a large pot of boiling, salted water, cook the ziti until just done, about 13 minutes. Reserve 3/4 cup of the pasta water and drain. Toss the ziti and 1/2 cup of the reserved pasta water with the mushroom mixture, the remaining 1 tablespoon oil, the goat cheese, and the Parmesan. If the pasta seems dry, add more of the reserved pasta water. Serve with additional Parmesan.