Position racks in the top and bottom thirds of oven; preheat to 425 degrees. On two large rimmed baking sheets, toss the squash and oil. Season with salt and pepper. Roast, turning once, until almost tender, about 35 minutes. Set aside 5 cups squash cubes. Roast remaining cubes until very tender, another 10 minutes; transfer to a food processor. Puree, adding water by the tablespoon if needed; let cool.
Freeze the cubes and puree separately in 1-cup portions.