How to cook
In a large oven dish, pour in 7 cups of flour and make a well. In the middle, put the water, egg, salt and butter. Begin to knead a dough until you've mixed in the 7 cups flour. Divide the dough into 5 balls and let them stand for 30 minutes, sprinkle them with a little flour.
Prepare the topping by mixing together the eggs, yogurt, baking soda and set it aside. Use the remaining 1 cup flour for sprinkling the top and bottom of the dough sheets while rolling them out. Roll out the dough balls as thinly as possible, because during baking, they will swell.
Brush the first rolled out sheet with butter and sprinkle it with feta cheese. Start rolling it up from the wide end into a spiral and arrange in a buttered oven dish. Repeat this process with the remaining sheets.
Brush with the remaining butter on top and pour the topping on. Bake the Turkish Burek at 390°F (200 °C) for about 40 minutes, or until browned.