Put 280 grams of flour, 0.5 teaspoons of baking powder, a pinch of salt, and 1/4 teaspoon of vanillin in a bowl and mix them together.
Mix the dry ingredients with 80 grams of butter until the dough looks like big crumbs.
Add one egg yolk and 200 grams of sour cream and mix well. Mix the dough until it holds together. It needs to be soft and bendy.
To make the filling:
Beat one egg white in a different bowl until it foams up.
After beating the egg white, add 40 grams of sugar and 1 teaspoon of vanilla sugar. Mix everything together well.
Chop up 100 grams of walnuts very small and add them to the egg white mix. Mix the stuffing until it's spread out evenly.

Putting it together: Cut the dough into small pieces and roll out each piece on a floured surface into a thin square.
Cover the rolled-out dough with the walnut filling.
Make a log shape with each piece of dough and seal the sides.
Cut the rolls into pieces that are 1 inch long.
Put the rolls on a baking sheet that has parchment paper on it.

Setting the oven to 180°C (356°F) and baking them for 15 to 20 minutes, or until they are golden brown.
Let the rolls cool down.
Add powdered sugar to the rolls after they have cooled.
Have fun with your quick and tasty Walnut Roll