Make a kneading dough from the dough ingredients, wrap in cling film and refrigerate for about 30 minutes.
Then roll out about 3 mm thin on a floured worktop. Use a pastry wheel to divide into approx. 4.5 x 3.5 cm rectangles. Place half of the rectangles on a baking sheet and, using two teaspoons, place a small dollop of plum jam in the middle of each rectangle. Place the remaining rectangles on top and press down on the edges.
Bake in a preheated oven at 200 ° C (fan oven: 180 ° C, gas: level 3) for about 10 minutes. Remove and dust immediately with decorative sugar. Let cool on a wire rack.