In a large bowl, put the milk, ? of the water and the trahana (cracked wheat or couscous). Let soak for at least 15 minutes. Separately beat 3 of the 4 eggs lightly and add 1/3 of the oil and the flour. After stirring well, add the milk with the trahana, the feta cheese and the zucchini; stir lightly. The mixture should be a fluid porridge. Pour into a relatively deep baking pan (35 cm). Spread the porridge evenly in the pan. Beat the 4th egg together with 1/3 of the water and spread lightly with an upside down spoon over the top.