8 tbsp. unsalted butter
3 lg. eggs, room temperature
2 egg yolks
1 1/2 c. sugar
1 1/4 c. pastry flour
1/4 tsp. salt
1 lemon peel, grated

Melt butter and cool. Preheat oven to 375 degrees. Using double boiler, combine eggs, egg yolks and sugar. Beat with an electric mixer until very, very pale yellow and thick and warm to touch, about 2 minutes.

Remove top pot from water and beat until mixture is completely cool and very thick, about 3 minutes. Sift the flour 3 times and add salt. Use a spatula to very slowly fold the flour into the eggs. Fold in the cool melted butter, then the lemon rind.

Butter and flour a 12 inch round cake pan with removable bottom, springform. Bake at 375 degrees for 30 minutes. Cool completely before removing from pan or the crusty top will crack.