To the 240ml of brewed espresso, add 240ml of boiling water. Pour 120ml of espresso into each of four (175 to 240ml) serving cups. Add two tablespoons of the spiced simple syrup to each cup and stir to combine.
In a large bowl, using an electric mixer with a whisk attachment, beat the double cream until soft peaks form. Add the icing sugar and continue to beat until stiff. Top each cup of espresso with a dollop of whipped cream. Dust with cinnamon and serve.