1-1/2 cups fine graham-cracker crumbs
2 tablespoons sugar
1/2 stick unsalted butter, melted and cooled
2-1/2 eight-ounce packages cream cheese, softened
3/4 cup sugar
1 cup sour cream
3 tablespoons all-purpose flour
3 large eggs
3/4 cup key-lime juice (available at specialty food stores and some markets), or fresh lime juice
1 teaspoon vanilla
Drop of green food coloring, if desired
Whipped cream, for garnish
Lime slices, quartered, for garnish
Mint sprigs for garnish
In a bowl, stir together the crumbs, sugar, and butter. Pat the mixture evenly onto the bottom and 1/2 inch up the sides of a buttered 10-inch springform pan, and bake the crust in the middle of a preheated 375 degree F. oven for 8 minutes. Transfer the pan to a rack and let the crust cool.
In a bowl with an electric mixer, beat together the cream cheese and the sugar until the mixture is smooth. Beat in the sour cream, the flour, the eggs, one at a time, mixing well after each addition. Then add the lime juice, the vanilla, and the food coloring, beating the mixture until it is smooth. Pour the filling over the crust.
Bake the cheesecake in the middle of a preheated 375 degree F. oven for 15 minutes. Reduce the temperature to 250 degrees F., and bake the cheesecake for 50 to 55 minutes more, or until the center is barely set. (The cheesecake will continue to set as it cools.) Let the cheesecake cool on a rack and chill it, covered, overnight.
Remove the cheesecake from the pan and transfer it to a cake stand. With a pastry bag fitted with a decorative tip, pipe the whipped cream into rosettes on the cheesecake. Garnish the cheesecake with the lime slices and the mint sprigs. Yields about 10 slices.