Cream the butter and sugar together, then mix in the ground almonds, rice flour, and cornflour.
Separate the egg yolk and white, keeping a little of the white for topping. Beat the egg and add it slowly to the mixture, mixing thoroughly.
Roll the mixture into balls and space them well on a tray lined with baking paper. Flatten them slightly with the back of a fork, then brush with the remaining egg white and decorate with sliced almonds.
Bake at 180°C for 10-12 minutes, or until lightly golden.
