Start by whisking together the butter, sugar and ground cinnamon until creamy and light and then add the beaten egg, flour and mix again until all combined.
Scrape the dough together and form it into a ball then wrap the ball into clingfilm and leave to cool in the fridge for 30 minutes.
Grease a baking tray and cover with grease-proof paper and remember to preheat your oven to 180C.
Then flour your worktop and roll the dough out to be roughly 0.5cm thick.
Cut out 6 of each star size (you might have to roll out the dough more than once). Place the cut out stars onto the baking tray and bake for 10 minutes then take the smallest ones out, bake the remaining ones for another 5 minutes.
To make the icing, sift half of the icing sugar into the egg white and whisk until smooth.
Now add the rest of the icing sugar and whisk again until smooth.
Using a small spoon or a paint brush, start by covering the largest star with icing.
Top the tips of the iced star with sprinkles then put the second star on top.
Cover the last star on the top with icing and with sprinkles and leave to dry.