Reminiscent of Sara Lee’s 1950s-era graham-cracker and sour-cream
cheesecake, this version features a thick layer of delicious sour cream
atop
the creamy filling and tart Key lime custard.

Lime custard

6 large egg yolks
3/4 cup sugar
6 tablespoons fresh Key lime juice or regular lime juice
1 teaspoon grated Key lime peel or regular lime peel

Crust

1 3/4 cups graham cracker crumbs (about 12 whole graham crackers)
1/4 cup sugar
1/2 teaspoon salt
1/2 cup (1 stick) unsalted butter, melted

Filling

2 (8-ounce) packages cream cheese, room temperature
2/3 cup plus 3 tablespoons sugar
2 large eggs
3 tablespoons fresh Key lime juice or regular lime juice
1 tablespoon grated Key lime peel or regular lime peel

1 16-ounce container sour cream

Thin lime slices

For lime custard:

Whisk all ingredients in heavy small saucepan over medium heat until
custard
thickens and boils for 30 seconds, about 8 minutes. Cool to room
temperature, stirring occasionally (mixture will thicken).

For crust:

Preheat oven to 350 F. Wrap 3 layers of foil around outside of 8- to 8
1/2-inch-diameter springform pan with 3-inch-high sides. Butter pan. Stir
first 3 ingredients to blend in medium bowl. Mix in butter until
moistened.
Press crumb mixture evenly onto bottom and 1 1/2 inches up sides of
prepared
pan. Bake just until set, about 5 minutes. Cool completely. Maintain oven
temperature.

For filling:

Place cream cheese, 2/3 cup sugar, eggs, lime juice, and lime peel in
processor; blend well.

Spoon custard into crust; smooth top. Carefully spoon filling over. Set
cheesecake in large baking pan. Add enough hot water to baking pan to
come 1
inch up sides of cheesecake pan. Bake until almost set but not puffed and
center moves slightly when pan is gently shaken, about 45 minutes.

Meanwhile, stir sour cream and remaining 3 tablespoons sugar in medium
bowl
to blend.

Carefully spoon sour cream mixture over hot cheesecake; smooth top. Bake
until topping sets, about 10 minutes. Cool 10 minutes. Run knife around
sides of pan to loosen. Cool cheesecake completely. Cover and refrigerate
overnight. Do ahead Can be made 2 days ahead. Keep refrigerated. Release
pan
sides from cheesecake; transfer to platter. Garnish with lime slices and
serve.