3 lb fresh spinach, stems discarded
3/4 tsp black pepper
5 Tbs unsalted butter
1/4 tsp freshly grated nutmeg
3/4 c finely chopped onion (1 small)
1 cup heavy cream or soy milk
3 garlic cloves, minced
4 lb butternut squash (2 large), peeled, quartered, and seeded
1 1/2 tsp salt
1/2 oz finely grated Parmigiano-Reggiano (1/4 cup)
Boil 1 in. water in a pot over high heat. Add spinach, a few handfuls at a time, and cook, turning with tongs, until wilted, 3-5 min. Drain and rinse under cold water.  Squeeze to remove excess moisture, then chop. Transfer to a bowl. Melt 3 T butter in a heavy skillet. Cook onion and garlic until softened, 3-5 min. Add onion mixture to spinach along with salt, pepper, nutmeg, and cream. Stir to combine.  Cut squash into 1/8-in-thick slices.  Layer squash and spinach mixture in baking dish, using about one fifth of squash and one fourth of spinach for each layer, beginning and ending with squash. Sprinkle top layer of squash with cheese and dot with butter, then cover directly with foil. Bake until squash is tender and filling is bubbling, 25-30 min. Remove paper and bake until browned in spots, 10-15 minutes, or broil 3 in. from heat, 2-3 minutes.