Mix milk, yeast and sugar to make leaven. Put it in warm place and wait till it doubles it's volume.
Sift the flour, mix with olive oil, add leaven and mix it well. Knead smooth and uniform dough. Put it in warm place and wait 45 min till it rises.
In the frying pan heat the oil, add onion, fry till change colour, add mushrooms, fry till done, sprinkle with black pepper.
Steam broccoli. When it cools down, slice.
Mix cottage cheese, milk, eggs, add lemon juice, black pepper, parsley. Divide mixture in half. Add fried mushrooms with onion to one half of the cheese & egg mixture. Add broccoli to the other half of cheese & egg mixture.
Brush muffin baking tray with oil.
Roll out the dough, cut in rectangulars and place them in "holes" of muffins baking tray.
Fill petit tarts with stuffing, half with broccoli, half with mushroom stuffing.
Bake in preheated oven, in 180 C degrees about 20-25 minutes, till golden brown.