Potato Gnocchi with Sage Cream

2 cups whole milk
1 teaspoon dried sage leaves
1 cup chopped onion
2−3 teaspoons margarine
4 cups small broccoflower, or broccoli, florets
1/2 cup water, divided
1 package (16 ounces) potato gnocchi, cooked, warm
2 tablespoons all−purpose flour
1/2 teaspoon ground nutmeg
Salt and pepper to taste
Shredded Parmesan cheese, for garnish