Preheat the oven to 325°F. Liberally butter a 9- or 10-inch springform pan, then press the crust into its bottom. Prebake the crust for 8 to 10 minutes, just until it begins to brown. Cool on a rack; the crust will harden as it cools.
Use an electric mixer to beat the egg yolks until light; add the cheese, lemon zest and juice, and 1 cup of the sugar and beat until smooth. Stir in the flour.
Beat the egg whites until they hold soft peaks; use a rubber spatula or your hand to fold them into the yolk-cheese mixture gently but thoroughly. Turn the batter into the prepared pan and place the pan in a baking pan large enough to hold it comfortably. Add warm water to the baking pan, so that it comes to within an inch of the top of the springform pan. Transfer carefully to the oven and bake until the cake is just set and very lightly browned, about an hour. Turn the oven up to 450°F if you’re making the sour cream topping.
Remove the cake from the oven and cool completely if not adding the sour cream topping. If you’re making the topping, combine the sour cream with the vanilla and the optional 1 tablespoon sugar and spread on the top of the cake. Return it to the oven for 10 minutes, without the water bath; turn off the oven and let the cake cool for 30 minutes before removing it. Cool on a rack, cover with plastic wrap, then refrigerate until well chilled before slicing and serving. This will keep in good shape for several days.
Ricotta Cheesecake. This is somewhat lighter (and far lower in calories, especially if you use part-skim ricotta): Substitute 1 1/2 pounds fresh ricotta for the cream cheese. Beat it in an electric mixer until lightened, then add the yolks. Increase the sugar to 1 1/4 cups; the flour remains the same. Substitute 1 teaspoon orange zest for the lemon zest, and use 1 additional teaspoon vanilla in place of the lemon juice. You can omit or include the sour cream topping, as you like. Bake as above.
Graham Cracker Crust
For any single-crust pie, 8 to 10 inches in diameter
Time: 20 minutes
To crumble graham crackers, place them in a heavy plastic bag and seal, then roll over the bag as many times as necessary with a rolling pin. Alternatively, break the crackers into the container of a food processor and process until crumbly. (Or buy graham cracker crumbs.)
6 tablespoons unsalted butter
6 ounces broken graham crackers, about 1 1/2 cups
3 tablespoons sugar
- Gently melt the butter in a small saucepan.
- Combine sugar with graham cracker crumbs in a bowl or food processor. Slowly add the butter, stirring or processing until well blended. Press the crust into the buttered springform pan as directed above.