Preheat the oven to 425°. In a small skillet, toast the cumin seeds over moderate heat until fragrant, about 2 minutes. Transfer to a spice grinder and let cool, then finely grind. On a large rimmed baking sheet, toss the butternut squash with the parsnip, onions, ground cumin, cardamom, ginger, nutmeg and 2 tablespoons of the olive oil. Season with salt and pepper. Roast for about 35 minutes, stirring once, or until the squash and parsnip are tender and lightly browned. Leave the oven on.