1. In a large bowl, combine 580 g flour, 250 g cold butter (cut into cubes), ½ tsp salt, 10 g baking powder, and 2 tbsp sugar.
2. Add 110 g sour cream (or Greek yogurt), 50 ml milk, and the 4 egg yolks.
3. Add 1 tbsp vanilla essence (or rum essence) and start kneading the dough until everything is well incorporated.
4. Once the dough is smooth, form it into a ball, sprinkle flour on the work surface, and divide the dough into 8 equal pieces.

1. Take one ball of dough and roll it out into a thin sheet with the help of a rolling pin.
   • If the dough is too soft, place it in the fridge for 30 minutes to make it easier to work with.
2. Place a plate on top of the dough and use a knife to trim the edges.
3. Divide the sheet into 8 equal wedges.
4. Place plum jam on the wide end of each wedge using a teaspoon.
5. Roll each wedge into a croissant shape and place the croissants on a baking tray lined with parchment paper.

1. Preheat the oven to 200°C (392°F).
2. Bake the croissants for 20 minutes, or until they are golden brown.

Let the croissants cool slightly, then dust them with powdered sugar before serving.