Beat the soft butter and brown sugar until light. Add the eggs one by one. Mix the cinnamon and baking powder with the flour and add to the butter-sugar-egg mixture. Stir into a smooth dough. Let the dough rest in cool place, for example in a refrigerator, for few hours. Roll the dough into strips about the thickness of your little finger. Cut the strips into 8-10 cm long pieces, and form the pieces into “S” shapes. Place the cookies on a baking tray covered with greaseproof paper. Bake at 200°C for about 10 minutes.