Place about 6-7 cups of water in a medium pot (make sure it more then covers the squash). Add squash after chopping into 1/2-inch circles. Add chopped onions to same pot. Add 1 1/2 tablespoons of margarine. Boil until completely cooked "really well".
Drain squash after done cooking.
Add squash and onions to casserole dish.
Add remaining margarine. Mix well until margarine is melted.
Add beaten eggs and mix well into squash.
Add 1/2 of the cheese into squash and mix well.
Add 1/3 of saltines into squash mix well.
Sprinkle on top the remaining cheese and saltines.
Bake at 350°F for 35-45 minutes until cheese melts completely.