To Make Dough Crust: Combine 1 cup of the flour, 1/4 cup of the sugar and 1 teaspoon grated lemon peel. Cut in the butter or margarine until the mixture resembles coarse crumbs. Stir in the beaten egg yolk and 1/4 teaspoon vanilla. Pat 1/3 of the dough into the bottom of one 9 inch springform pan with the sides removed. Bake at 400 degrees F (205 degrees C) for 6 minutes. Let cool then butter sides of pan and attach to bottom. Pat the remaining dough evenly on the sides to a height of 2 inches.
To Make Filling: Preheat oven to 500 degrees F (260 degree C). Stir cream cheese to soften, then beat until fluffy add 1/8 teaspoon vanilla and 1/2 teaspoon grated lemon peel.
Mix 1 1/2 tablespoons flour, 1/8 teaspoon salt and the remaining sugar together. Gradually blend this mixture into the cream cheese mixture. Add the eggs and the egg yolk one at a time, beating well after each one. Gently stir in the heavy cream. Pour batter into the prepared crust.
Bake at 500 degrees F (260 degrees C) for 5 to 8 minutes or until top edge of crust is golden. Reduce heat to 200 degrees F (100 degrees C) and continue baking for 1 hour. Remove cake from oven and cool in pan for at least 3 hours. Remove sides of pan to serve.
