Southeast Asian Squash Curry

Heat 1 tablespoon oil in a 12-inch heavy skillet over medium-high heat until it shimmers. Sauté squash with cumin and 1/4 teaspoon salt until beginning to brown, about 6 minutes. Transfer to a plate. Add remaining 2 teaspoons oil to skillet and cook onion over medium heat, stirring occasionally, until softened, about 5 minutes. Add 1/4 cup coconut milk from top of can and cook, stirring, until fat starts to separate and look glossy, about 2 minutes. Add curry paste and cook, stirring, 2 minutes. Add squash, water, cinnamon, cloves, and remaining coconut milk and simmer, covered, until squash is tender, about 8 minutes. Stir in spinach and cook, covered, until just wilted, 1 to 2 minutes. Stir in fish sauce. Sprinkle with cashews.