For the dough
2 cups flour (250g)
250 g cold butter
4 egg yolks
100 ml sour cream
For the filling
4 egg whites
1 cup sugar
1/2 cup finely chopped walnuts
Dough
Grate the butter into a bowl with flour
Add yolks and sour cream
Form the dough using a food processor/mixer
Divide the dough into 8 balls, wrap each ball with plastic wrap and refrigerate for 30–40 minutes
Filling
Beat egg whites with sugar until thick foam forms.
Roll each dough ball into a circle, about 2–3 mm thick (on a floured surface)
Spread meringue filling on each circle and sprinkle with nuts
Cut each circle into 8 parts, like a pizza (triangles)
Roll each triangle into a rogalik (from wide side to narrow tip)
Bake at 180°C (350°F) for about 20 minutes until golden