Whisk the egg whites until they form
stiff peaks. Whisk in the caster sugar a little at a time. Fold in the
ground almonds. Using a 1 cm/0.5 in piping nozzle (tip), pipe the
mixture into 5 cm/2 in lengths on a lightly oiled baking (cookie)
sheet. Bake in a preheated oven at 140°C/ 275°F/gas mark 1 for 1-1.5
hours. Leave to cool.
Cream together the butter or margarine, icing sugar and cocoa.
Sandwich pairs of biscuits (cookies) together with the filling. Melt
the chocolate in a heatproof bowl over a pan of gently simmering
water. Dip the ends of the meringues in the chocolate and leave to
cool on a wire rack.