Work the flour, baking powder, butter, sugar, oat flakes and salt into a crumbly mass. Add the syrup, cranberries, raisins and water and work everything into a firm dough. Carefully roll the dough into a long or several small sausages, approx. 5-7 cm in diameter. Place the dough in the refrigerator for about 30 minutes, ideally wrapped in plastic wrap.
Preheat the oven to 200 degrees Celsius.
After cooling, cut the dough rolls into approx. 1 cm thick slices and place them on a baking sheet lined with baking paper.
Reduce the temperature of the oven to 175 degrees Celsius and bake the biscuits for 10-15 minutes in the middle rack, leave to cool on a wire rack.