In a mixing bowl, combine butter, powdered sugar, and egg yolk (reserve the whites for later use).
Add salt, yogurt and sifted flour with baking powder. Mix everything together and knead until a smooth dough forms.
Wrap the dough in foil and refrigerate it for at least 30 minutes.
Remove the dough from the refrigerator and divide it into 4 equal parts. Roll out each part and cut it into triangles, it's best to use flour to prevent dough from sticking.
Place a teaspoon of jam at the base of each triangle, roll it up to form crescent rolls. Brush with water to help seal the dough.
Place the crescent rolls on a baking sheet lined with parchment paper. Brush with reserved egg whites and sprinkle with sugar.
Bake in a preheated oven at 175 °C for 20 minutes. Enjoy!