Wash the squash and slice the squash and put the squash and onions in a large saucepan. Put half water in the squash saucepan and put salt and pepper in squash. Bring to a boil and reduce medium heat and let it cook until tender. Drain the water and put the squash back in the saucepan and add egg, 1/2 cup cheese, and 1/4 cup ritz crackers in squash mixture and stir well. Put the squash in 10X10-inch baking dish and sprinkle 1 1/2 cups cheese and 3/4 cup ritz crackers on top of squash. Add the melted butter on top of ritz crackers. Bake at 350 F. for 30 minutes until cheese melted and golden brown.