How to cook
Cut the zucchini into very thin slices and saute them in a saucepan with the butter and oil, while stirring constantly so that they saute evenly (about 15 min.).
Once the zucchini have sauteed (when they change color), take them out with a slotted spoon into a plate or bowl and prepare the sauce in the same pan (without washing it).
Add the butter and oil for the sauce, add the chopped into crescents onions, braise lightly, then add the finely chopped garlic and parsley and the flour, braise until the flour turns yellow and while stirring nonstop, add the water and tomato paste.
Also add the sugar and salt to taste and let it simmer 1-2 min. Remove the prepared sauce from the stove. In a small bowl, beat the egg, pour in the yoghurt and stir well.
Once the zucchini, sauce and yoghurt are ready, arrange a layer of the zucchini in a suitable oven dish, pour on half the sauce, distribute half the yoghurt/egg mixture, then place another layer of each of these in the same order.
Bake at 392°F (200 °C) for about 30 min. or until ready.