Step 1

Place egg whites in a large bowl; let stand at room temperature for 30 minutes. Grease and flour a 13x9-in. baking pan. Preheat oven to 375°.

Step 2

Beat sugar, tequila, butter, yolks, 3 tablespoons lime juice and vanilla until well blended. Combine flour, baking soda and salt; gradually beat into yolk mixture until blended.

Step 3

Add confectioners' sugar and cream of tarter to egg whites; beat with clean beaters until stiff peaks form. Fold into batter. Transfer to prepared pan.

Step 4

Bake until a toothpick inserted in the center comes out clean, 18-20 minutes. Place pan on a wire rack. With a wooden skewer, poke holes in cake about 1/2 in. apart.

Step 5

Beat condensed milk, 2% milk, evaporated milk, whipping cream and remaining 3 tablespoons lime juice until blended. Drizzle over cake; let stand for 30 minutes. Refrigerate for 2 hours before serving.

Step 6

Cut cake into squares. If desired, garnish with whipped cream, and lime slices and zest.