Brûléed Key Lime Tarts

10 Oreo cookies
2 tablespoons melted butter
5 egg yolks
One 14-ounce can sweetened condensed milk
2/3 cup Key lime juice
Finely grated zest of 1 lime
3 tablespoons granulated sugar, plus 8 teaspoons for sprinkling
3 kaffir lime leaves (optional)
Pinch of salt

Preheat the oven to 350 degrees. In a food processor, finely grind the Oreos. Pulse in the butter. Lightly spray four 4 1/2-inch fluted tartlet pans with removable bottoms; press the ground Oreos into the bottoms. Set the pans on a baking sheet and bake for 8 minutes, or until the edges look dry. Let cool.

In a bowl, whisk the yolks, condensed milk, 1/3 cup of the Key lime juice and the lime zest. Pour the filling into the pans and bake at 325 degrees for about 15 minutes, until the edges are just firm. Let cool for 30 minutes, then freeze until very cold, about 2 hours.

In a small saucepan, combine the 3 tablespoons of sugar with 3 tablespoons of water, the lime leaves and the salt. Cook until the sugar has dissolved, then let cool. Discard the lime leaves. Stir in the remaining 1/3 cup of lime juice and refrigerate.

Sprinkle 2 teaspoons of the sugar over each tart and caramelize with a blow torch. Unmold the tarts and place in shallow bowls. Pour in the Key lime sauce and serve. Serve with sweetened whipped cream.