Set oven at 350° F. Grease and dust with flour a 9" kugelhopf pan or a deep 9" tube pan. Arrange blanched almonds around bottom of pan.
Add vanilla and grated lemon rind to butter, melted over low heat and cooled to lukewarm - not clarified butter!
In a large bowl combine eggs, egg yolks and sugar. Beat for a minute. Set bowl over a saucepan of hot - not boiling - water, and place saucepan over very low heat for about ten minutes - or until eggs are slightly warmer than lukewarm. Do not let water boil. Stir eggs occasionally while they are being heated to prevent them from cooking on bottom or sides of bowl.
When eggs are warm, beat until they are cool, thick and tripled in bulk. This takes about 10 - 12 minutes with the electric beater at high speed. Sprinkle flour, cornstarch and mace on top. Fold in gently, adding butter at the same time. Continue to fold until there is no trace of butter. Be CAREFUL not to overmix.
Pour batter into prepared pan. Bake about 45 minutes, or until cake is golden brown and comes away from sides of pan.
The cake should be left in the pan for 15 - 20 minutes after baking, then turned out on a cake rack to finish cooling. The cookbook says it shouldn't be sliced for 24 hours, but we can't wait that long.
Dust with xxxx sugar before serving.