Heat olive oil in a large skillet over medium heat. Add diced onion and minced garlic, and cook until softened, about 3-4 minutes.
Stir in curry powder, ground turmeric, ground cumin, ground coriander, and cayenne pepper (if using), and cook for 1 minute until fragrant.
Add diced squash to the skillet and cook for 5 minutes, stirring occasionally, until slightly softened. 4.Pour in coconut milk and stir to combine. Bring the mixture to a simmer, then reduce heat to low and let it cook for 15-20 minutes, or until squash is tender and curry has thickened.
Season with salt and pepper to taste. Serve hot, garnished with chopped fresh cilantro if desired.
Notes
To save time, you can purchase pre.cut butternut squash from the grocery store.
For added protein, try adding cooked chickpeas or tofu to the curry.
Feel free to customize the level of heat by adjusting the amount of cayenne pepper or adding chopped chili peppers to the dish.