Beat the almonds with the sugar, vanilla
essence and one of the egg whites until smooth. Beat in the liqueur.
Whisk the second egg white until stiff and fold into the mixture with
a metal spoon. Divide the mixture into walnut-sized pieces and roll
into balls. Place on a baking (cookie) sheet lined with baking
parchment and press a flaked almond on top of each ball. Bake in a
preheated oven at 180°C/350°F/gas mark 4 for about 25 minutes or until
golden brown. Leave the biscuits (cookies) on the baking sheet for 5
minutes then dust with sifted icing sugar and transfer to a wire rack
to cool. Store in an airtight container.