3 butternut creamed spinach gratin Recipes

fresh spinach , stems discarded, or 3 (10-oz) packages frozen leaf spinach, thawed, unsalted butter plus additional for greasing pan, chopped onion (1 small), garlic cloves, minced, salt, black pepper, freshly grated nutmeg, heavy cream, butternut squash (2 large), peeled, quartered, and seeded, grated parmigiano-reggiano (1/4 cup)

butternut squash , necks only, peeled and each cut crosswise into sixteen 1/4-inch-thick rounds, extra virgin olive oil, salt & freshly ground black pepper, cleaned spinach, stemmed and rinsed, heavy cream, creme fraiche, freshly grated parmesan cheese