Preheat oven to 350 F.
Cut out 2 pieces of parchment paper about 12”x14”.
In a bowl, combine flour, cinnamon, baking powder and salt.
In the bowl of an electric mixer, cream butter and sugar until creamy.
Add half of the egg and mix until incorporated.
Add the dry ingredients and mix until just combined.
Place one piece of the cut parchment paper on a work surface.
Transfer the cookie dough to the parchment.
Sprinkle a little flour on top and roll out the cookie dough to 10”x12”.
Use your hands to help shape the dough.
Brush the top of the dough with the remaining half of the egg.
Sprinkle almonds and rock sugar on top.
Place the other piece of parchment on top and with a rolling pin roll over the dough, to press the almonds and sugar inside the dough. Remove top parchment paper.
Lift parchment paper with dough and transfer to cookie sheet.
Bake for 15 minutes.
Using a sharp knife, cut into 18 pieces.
Bake for 5-8 minutes until cookies are slightly firm.
Leave to cool completely on tray.
Separate cookies and store in an air tight container.