Gradually add the flour and knead for about 10 minutes, until smooth and elastic.

Let the dough cold-ferment in the fridge for about 2 days. (If short on time: room-temperature rising for 4–6 hours works, but gives less tang.)

Mix butter, almond paste, granulated sugar, vanilla sugar, cardamom, cinnamon, flour, syrup, and salt into a smooth but firm paste.

Mix egg yolk, salt, and a few drops of water for the egg wash.

Gently brush the buns and sprinkle with pearl sugar.

Bring the sugar and water to a boil to make a simple syrup.

Brush the buns with the syrup right when they come out of the oven.

Dust with powdered sugar if desired.

Let cool slightly before serving.

Roll the dough out into a rectangle, about 30×50 cm.

Spread the filling evenly, all the way to the edges.

Roll the dough up into a long log.

Cut the log into pieces about 2–3 cm thick.

Place the buns in bun molds on a baking sheet lined with parchment paper.

Let rise for about 30–40 minutes, until the buns have visibly increased in size.

Preheat the oven to 225°C (440°F).

Bake for about 10 minutes, until golden brown.