Squash Casserole

I had this (or something like it) at a BBQ a few months ago. It was really good. I searched online for some recipes and thought this one sounded most like what I had. I think I'll try to make it.

Ingredients:

2 pounds small yellow squash

1 medium onion, chopped

Water

Salt to taste

2 cups grated mild cheddar cheese (reserve some for the topping)

1 cup whole milk (or use 1/2 milk and 1/2 heavy cream)

3 tablespoons butter, melted

1 egg, beaten

2 cups Ritz cracker crumbs (save some for the topping)

Directions:
Wash the squash well and cut into bite size chunks, place in a pot with the chopped onion, add about 1 1/2 cups water, sprinkle with some salt. Bring to a boil, reduce the heat and simmer until the squash are just barely tender. Drain well and set aside to cool slightly. In a large mixing bowl, mix the squash/onion mixture, cheese (save some for the topping), melted butter, milk, egg and about 3/4 of the cracker crumbs. Mix gently until all is combined. Pour into a lightly greased or buttered baking dish. Combine the reserved cheese and crumbs and sprinkle over the squash mixture. Bake in a 350: oven about 25-30 minutes.