1 butternut squash, peeled1 bunch kale or other greens1 large onion3 cloves garlic3 tablespoons olive oilSalt and pepper2 cups diced tomatoes1 tablespoon chopped fresh sage leaves1 cup grated Gruyere, mozzarella or fontina cheese, for toppingCarefully cut the squash in half lengthwise, then scoop out the seeds. Place the halves face-down and cut in Z\v-inch-thick slices.Remove and discard the stems from kale or other greens. Chop the leaves roughly.Dice large onion and mince cloves of garlic. Saute the onion in olive oil until soft, then add the garlic and cook another minute.Add the kale and cook for 5 minutes. Season to taste with salt and pepper.Lightly grease a 13-by-9-inch baking dish or large cast iron skillet, then cover with an overlapping layer of squash slices. Sprinkle with salt and pepper. Spread the cooked greens over the squash, then make another layer of squash.Spoon 2 cups of diced tomatoes and 1 tablespoon chopped fresh sage leaves over this layer, then make another layer of squash. Top with grated Gruyere, mozzarella or fontina cheese.Bake the casserole at 350 degrees for 45 minutes or until it is brown on top and bubbling.Note: If you use greens other than kale, or in addition to it, be sure to drain the cooking liquid before adding to the casserole.