Cream the butter with the sugar and lemon rind until light. Add the egg yolks, one at a time, and beat well.
Press the hard cooked egg yolks through a sieve and add to the creamed mixture along with the lemon juice and grated lemon rind. Stir in the blanched (no skins) nuts, and then the flour; mix thoroughly.
Break off small pieces of dough, roll into finger lengths of pencil thickness, and shape them into rings.
Mix finely chopped almonds with the 1 cup sugar.
Dip each ring into a slightly beaten egg white and then into the almond-sugar mixture.
Place the rings on a greased baking sheet and bake them in a moderate oven (350 degrees F.) for 15 minutes, or until delicately browned.