Place the mango in the freezer for 30 minutes to allow it to cool. If you are in a hurry you can skip this step and add 2 ice cubes into the smoothie instead. Remove the skin of the mango with a food peeler, Cut mango into medium chunks, reserve about 1 teaspoon of mango to use later for garnish on the smoothie (dice the reserved mango into small peices) .
Place the mango, Greek yogurt and 1/4 teaspoon cinnamon in the blender. Blend for 2-3 minutes on high or until the mixture is creamy. Use a spoon to scrape the edges of the blender if any mango get's stuck on the sides. Pour into a cup, top with the reversed mango and lightly sprinkle with cinnamon.