Preheat oven to 350 degrees F. Lightly grease a 2 1/2-quart casserole dish.
In a large Dutch oven, combine squash and onion; add water to cover. Bring to a boil over high heat and cook 10 to 12 minutes or until squash is tender; drain well. Spoon squash mixture into a large bowl.
In a small bowl, whisk together eggs, milk, curry powder, salt, and pepper. Add to squash mixture. Beat at medium speed with an electric mixer until smooth. Spoon into prepared baking dish; sprinkle evenly with raisins and coconut. Bake 40 minutes or until center is set.