Cook sliced zucchini until very tender. Drain. Place in bowl and mash well. Add onion, soy sauce, salt, pepper and parsley.
Melt 2 tablespoons butter in saucepan over low heat and whisk in flour to prevent lumps. Gradually stir in milk or pareve milk to make a white sauce. Stir this into zucchini mixture.
Beat eggs and add to vegetable mixture. Melt remaining 2 tablespoons of butter in 9x13 Pyrex baking dish. Pour in zucchini mixture and bake uncovered for 45 minutes at 350 degrees or until top is golden brown. Serves 6.
1 small cauliflower, 1 medium eggplant, 2 cups frozen peas or 1 pound string beans may be substituted for the zucchini.
