1 1/2 cups graham cracker crumbs
1/4 cup (1/2 stick) unsalted butter, melted
1/4 cup pine nuts
2 tablespoons sugar
1 14-ounce can sweetened condensed milk
4 large egg yolks
1/2 cup fresh lime juice
1/4 cup tequila
2 egg whites
1 tablespoon sugar
Whipped cream or sliced limes (optional)
For crust, blend all ingredients in processor until small clumps form. Press mixture onto bottom and up sides of 9-inch-diameter tart pan with removable bottom. (Can be made 1 day ahead; chill.)
Set oven at 325 deg F. For filling, stir condensed milk and next 3 ingredients in medium bowl to blend. In another bowl, beat egg whites with sugar in large bowl until soft peaks form. Using rubber spatula, gently fold 1 1/2 cups condensed milk mixture into whites. Fold remaining milk mixture into whites until just incorporated.
Pour mixture into prepared crust. Bake until filling puffs up slightly and tester inserted into center comes out with some moist filling attached, about 40 minutes. Cool tart completely on rack. Chill until cold, at least 2 hours and up to 8 hours. Garnish tart with whipped cream and lime slices.