Butternut Squash Gratin With Creamed Spinach

2 (2 lb) butternut squash, necks only, peeled and each cut crosswise into sixteen 1/4-inch-thick rounds 1 tablespoon extra virgin olive oil salt & freshly[...]

4 -5 lbs butternut squash, usually 2-3 large, peeled and seeded 4 (10 ounce) packages frozen spinach , chopped and well drained 1 onion , halved and thin[...]