Preheat the oven to 200 degrees C or 400 degrees F. Combine almonds and icing sugar in a large pan. Add the unbeaten egg white and mix to a firm dough. Place the pan over a low heat and knead until dough is so hot that it is too hot to handle. Grease a 16-18 inch ring cake pan. Spoon the dough into a pastry tube with a wide round tip and press the dough into the ring, blending the ends together. Bake for 12-15 minutes until dry and firm outside, soft inside. Take out and leave to cool. 
For the icing sift the sugar and mix with egg white until nice and thick. Put in a piping bag and pipe on garlands of icing on top of each other and decorate with flags, bonbons or candy.
.
.
.