Preheat the oven to 375° F.
To prepare the crust, in a large bowl, combine the flour, sugar, and lemon zest. Using a pastry blender or two knives, cut in the butter until the mixture is crumbly. Using a fork, stir in the egg yolk and vanilla until all the dough is moistened.
Pat one third of the crust over the bottom of a 9-inch springform pan with its sides removed. Bake for about 6 to 8 minutes, or until golden brown. Cool.
Grease the sides of the springform pan and attach to the bottom. Pat the remaining two thirds of the crust around the sides, coming up to a height of about 2 inches.
Increase the oven temperature to 475° F.
In a large mixing bowl at medium speed, beat together the cream cheese, sugar, and salt until creamy. Add the vanilla extract. Add the eggs and egg yolks, one at a time, beating well after each addition. Add the sour cream and mix well. Pour the mixture into the prepared crust.
Bake for 10 minutes. Watch the top of the cake to avoid overbrowning.
Reduce the oven temperature to 200 degrees F and bake for an additional 60 minutes.
Transfer the pan to a wire rack to cool slightly, about 10 minutes.
While the cake is still warm, gently run a thin-bladed knife around the inside edges of the pan to loosen the sides of the cake. When completely cool, carefully remove the sides of the pan. Chill for at least 2 hours before serving.
Makes: 12