Cream together the butter and sugar until light and fluffy. Add the egg, vanilla and almonds; mix a few seconds until well incorporated. Stir in the flour until a dough forms.
Roll the dough into a rope 2cm thick. Cut the rope into 8cm long pieces. Shape the biscuits by rolling each piece back and forth while pressing down gently with two fingers on each end until the piece is about 12cm long. The dough piece should be plump in the center, and thinner on it's ends. Repeat with remaining biscuits.
Place the biscuits onto a baking tray, bending the ends toward each other to form a crescent 'C' shape. Bake in preheated oven until the edges have turned golden brown, about 20 minutes. Dust immediately with powdered sugar, then cool completely on a wire rack.