First, grate the ham and cheese on a grater. Drain the champignons and cut into smaller pieces. Stir in the tomato puree some oregano and a pinch of salt and pepper.
Coat a round pizza pan with a diameter of 32 cm with oil, then place the first layer of filo dough on it and coat it with oil, then place the second layer of dough on it. Then it depends on the number of layers of filo dough you have, how many you will stack. The bottom layer of dough, looking over the baking tray, is left to fold at the end, the rest is always folded into the baking tray and moisten either with the filling (take turn adding ham, cheese, champignons and tomato sauce, or even mix them a little) oil or water to make the burek juicy and not dry. Be extra general around edges. Coat the last layer with oil and bend it in a baking dish to get a nicely finished burek. The intermediate layers can be filled or moistened as desired.
Finish by coating it with oil and before baking, press down on the burek with hands and also poke it with a fork a couple of times. Then bake for up to 35 minutes at 200 degrees Celsius.
Once you take the burek out of the oven, sprinkle it with water and cover with a cloth to soften the crust.Cut into pizza pieces and serve warm.