For the cinnamon mixture, simply mix the cinnamon and sugar and set aside.
For the dough, beat the butter with the sugar until very frothy. Then stir in the egg. Mix the flour, baking powder, salt and cinnamon together. Gradually stir into the butter.
Press out the dough into a rectangle of 20 x 30 cm and sprinkle with 1/2 of the cinnamon mixture, leaving about 1 cm at the edge. Then roll up the dough from the broad side. Roll in the rest of the cinnamon mixture. Put the rolls in the refrigerator for a few hours.
Preheat the oven to 175 ° C.
Cut the dough into about 5 mm thick slices and place on a prepared baking sheet. Bake until golden brown for about 8 minutes. Then leave to cool on the baking sheet for about 5 minutes, then transfer to a wire rack.
Makes around 60 cookies.
You can of course also use normal butter and 405 flour.