In a large bowl, beat the egg yolks until light. Add the water, salt, pepper, and half the matzo meal. Blend together. In a separate bowl, beat the egg whites until stiff. Fold the egg whites into the yolk mixture; add the remainder of the matzo meal.

In a large skillet, melt the butter over medium heat. Drop the matzo meal mixture by the tbsp into the butter and fry on each side until light brown. Remove the batter cakes from the skillet and arrange them in a 9x13 inch baking pan.

Saute the onion and the mushrooms in the skillet over medium heat, adding add'l butter if necessary, until golden brown. Remove the skillet from the heat. Add the tomatoes and cheese to the pan; mix well. Pour the mixture over the batter cakes in the baking pan. Bake in a 325°F oven for 45 minutes. Serves 4-6.

arrange the pieces in the baking dish. Continue as above.