Preheat your oven to 350°F or 175°C (350°F).
Line two large baking pans with foil for easy cleanup.
Prepare the squash: Peel the butternut squash, slice it in half lengthwise, and use a spoon to scoop out the seeds.
Chop the flesh into uniform ¼-inch-thick half-moons.
Roast the squash: Tumble the squash onto the prepared pans, drizzle with a couple of tablespoons of oil, and use your hands to toss until every piece is lightly coated.
Roast for 35 to 45 minutes, flipping halfway through, until tender and beginning to caramelize at the edges.
Make the crispy onions: While the squash roasts, heat a couple of tablespoons of oil in a skillet over medium heat.
Add the thinly sliced onion and fry for 15 to 20 minutes, stirring occasionally, until deeply caramelized and crisp.
Remove from the heat and set aside.
Blend the cafreal sauce: Roughly chop the cilantro, ginger, garlic, and green chiles.
Add them to a high-speed blender along with the ground cumin, cinnamon, lemon juice, salt, black pepper, and the entire can of coconut milk.
Blend until you have a smooth, vibrant green sauce.
Cook the sauce: Pour the blended sauce into a deep saucepan or pot over medium heat.
Let it cook gently for 5 minutes, stirring occasionally, to allow the flavors to meld.
Combine and serve: Add the roasted butternut squash to the saucepan with the cafreal sauce.
Stir gently to coat and cook for another 5 minutes to heat through.
Transfer to a serving dish, generously scatter the crispy fried onions on top, and serve immediately with fluffy rice.
