Meanwhile, in a large skillet over medium-high heat, heat remaining 2 tablespoons oil. Add onion, season with salt, and cook, stirring occasionally, until lightly golden, 8 minutes. Reduce heat to medium-low. Add garlic and cook, stirring, until fragrant, about 1 minute. Add curry powder and cook, stirring, until combined. Increase heat to medium and add coconut milk. Bring to a simmer, then add kale; season with salt. Cook, stirring occasionally, until tender and wilted, about 3 minutes. Remove from heat until squash finishes roasting.