Bring salted water to boil. Add zucchini for aprox 3 min. Drain well.
saute chopped onion till sl. translucent.
In a blender or food processor add mayo, parm. cheese. dijon mustard, and eggs pinch of salt and pepper and blend till well mixed.
Put zucchini in a buttered 8x11 baking dish. Mix in onions. Pour blended ing over top. Bake for 25min. remove from oven and top with crushed ritz cracker and melted butter return to oven for 5 min.