Dissolve the yeast in warm milk,and leave it for 15 mins. Mix the flour with the salt and sugar,add the egg, milk and yeasty milk.Knead it for 10 minutes.Add the melted butter and knead for another 5 minutes.Cover it and leave it in a warm place for about one hour, until it doubles in size.

Make the filling. In Hungary we use creamy cow's curd, but if you dont have it, try to substitute it with ricotta or cottage cheese. We mix the cow's curd with semolina,sugar, vanilla essence,lemon zest,sultanas, and egg yolks. Beat the egg whites until firm and add it to the ricotta mix. The texture should be creamy but not runny. If it's runny then add more semolina.

On a floured surface, roll the dough out with a rolling pin, until approximately 3 mm thick. Cut it into 10×10 cm squares. Put a tablespoon of ricotta mix in the middle of each square. Pinch all 4 corners together and pinch it together.

Put them on a parchment paper on a baking tray, cover them, and let them rise again for 30 minutes.Preheat the oven to 180 degree celsius, or gas level 6. Once risen, glaze them with the beaten egg and bake them for 25-30 minutes.