Butternut Squash Mac and Cheese

butternut squash (peeled, seeds removed, cut into 1-inch cubes)1 cup low-sodium chicken broth1 cup milkKosher salt and black pepper, to taste2 Tablespoons unsalted butter1/4 teaspoon ground nutmeg1 cup cheddar cheese1 lb. (about 2 cups) elbow macaroni