1Preheat the oven to 350°F.
2In a medium bowl, stir together the graham crumbs and melted butter. Press into the bottom and halfway up the sides of a 9-inch (not deep dish) pie plate. Bake for 10 minutes, or until just pale golden around the edges.
3In another medium bowl, whisk together the sweetened condensed milk and egg yolks until smooth. Whisk in the lime juice - the mixture will thicken slightly. Pour into the crust and bake for 15 minutes, until just set.
4Cool, then refrigerate for a few hours, or overnight. Serve topped with whipped cream.