Heat oven to 350°F. Let cookie dough stand at room temperature 10 minutes to soften.
Meanwhile, spread 1/2 cup of the coconut in ungreased shallow pan. Bake 5 to 7 minutes, stirring occasionally, until golden brown. Cool 5 minutes. In small bowl, mix toasted coconut and lime zest until well blended; set aside.
Break up cookie dough and press in ungreased 13x9-inch pan. Bake 15 to 20 minutes or until light golden brown. Cool completely, about 30 minutes.
In 1-quart saucepan, cook sweetened condensed milk and butter over medium heat, stirring constantly, until butter is melted and ingredients are thoroughly heated. DO NOT BOIL. Remove from heat; stir in white baking chips until melted. Stir in remaining 1 cup coconut and the vanilla.
Pour coconut mixture over cookie crust, spreading evenly. Sprinkle with coconut lime mixture; press in lightly. Cool 15 minutes. Refrigerate 1 hour or until topping is firm.