Grease cookie sheets well. Mix sugar, ground almonds, and cinnamon. Beat egg whites until stiff but not dry. Gently stir in ground almond mixture. Drop by teaspoonfuls 5 cm apart onto cookie sheets. Sprinkle with a sliced almond or two on top of each. Bake 180ºC for 10 minutes until golden brown. Cool 2 minutes before removing to wire rack. If the last few stick, return pan to oven to reheat and remove cookies immediately. ----