1) Preheat the oven to 180C/Gas 4. Lightly grease a 2L casserole dish.
2) In a large Dutch oven, combine the squash and onion; add enough water to cover. Bring to a boil over high heat and cook for 10 to 12 minutes or until the squash is tender; drain well. Spoon the squash mixture into a large bowl.
3) In a small bowl, whisk together the eggs, milk, curry powder, salt and pepper. Add to the squash mixture. Beat at a medium speed with an electric mixer until smooth. Spoon the mixture into the prepared baking dish; sprinkle evenly with the sultanas and coconut. Bake for 40 minutes or until the centre is set.