Start by making the crepes. Whisk together the flour, sugar and salt then add the egg and oil.
Gradually and slowly pour in the milk whisking (quite vigorously) all the time until smooth. If there are any lumps left use a stick blender to get the batter as smooth as possible. Set aside for 5 minutes.
To make the fillingsimply stir all the ingredients together using a large spoon or fork. Adjust the amount of yogurt or sugar to taste. Set aside.
Heat up about 2 teaspoons of oil spreading evenly in the pan then ladle the batter swirling it around to make sure it spreads over the entire surface of the pan.Don't be afraid to make these crepes quite thin, they won't tear easily. They need about 2 minutes on one side and a minute on the other (cooked over a medium heat).
Cover each crepe with a thin layer of the cheese mixture and fold. Dust with a little powdered sugar (optional) and enjoy!
You can make these crepes large or small, depending on how big your pan is.
Once you've made the crepes batter set is aside for a few minutes. This is a good time to make the filling.
Adjust the amounts of sugar and yogurt in the filling mixture according to taste. If using creamy substitutes for twarog (such as cottage cheese or quark) omit the yogurt.
Make ahead: These crepes can be made ahead (with or without the filling) and once cooled, covered and refrigerated for up to 2 days.
Serve hot or cold. Once you've folded the crepes you can either heat them up in the microwave or briefly fry them in a little butter. Alternatively serve cold.
Twarog: use creamy cottage cheese, quark, fromage frais/fromage blanc instead.
Yogurt: use sour cream instead, alternatively use vanilla flavoured yogurt and omit the vanilla extract.
Vanilla extract: vanilla bean paste is a good substitute.
Oil in the batter can be replaced with melted butter.