Pappardelle with Squash Mushrooms and Spinach

Name: Pappardelle with Squash, Mushrooms, and Spinach
Ingredients: 12 ounces pappardelle or fettuccine pasta; 1/2 cup (1 stick) butter, divided; 3 cups 1/2-inch cubes butternut squash (from 1-pound squash); 8 ounces fresh shitake mushrooms, stemmed, caps sliced; 1 1/2 tablespoons chopped fresh sage; 1 5-to-6-ounce package baby spinach; 3/4 cup grated Parmesan cheese, divided