Mix the flour, yeast, salt, sugar, milk and water into an even batter. Add the oil and stir well again. Let the dough rise in a warm place for an hour, until it is about twice its volume. Mix with a spoon and press down, then let rest for another 30 minutes.
When the walking time comes to an end, cut the 3 types of cheese into small pieces (cubes of a few millimeters) and mix them in a bowl.
Preheat the oven to 230 degrees. Divide the dough into 4 equal pieces and roll them out into 20 cm circles on flour or directly on baking paper. Roll from 2 opposite sides in the middle until about 5 cm are free in the middle. Then press the open ends together so that you have small boats.
Spread the cheese on the boats. Mix an egg with a little water and use a brush to brush the uncovered dough. The boats are now in the oven for 15 minutes. Then make a hollow in the cheese in the middle and beat in an egg at a time. The hollow should be big enough so that the egg white cannot leak out. Then put it in the oven again for about 5 minutes. The egg white should not be quite firm yet.
Serve fresh from the oven. The cheese and the still soft egg are mixed with a fork and become a dip for the bread.