Dissolve the yeast in warm water with sugar. Mix and add flour, milk and salt to it. Knead a dough and let it rise until double in volume.
Divide the dough into 2 parts. Each is rolled out to the size of the tray in which you intend to cook it. It is better for it to be larger. Roll out the first layer, brush it with melted butter and sprinkle it with chopped olives. Put the second on top.
Brush it with beaten the egg yolk and yoghurt. Make a decoration from a few chopped olives and onions and put it to bake at 356°F (180 °C) in a preheated oven until nicely reddened.