Whisk zest and yolks in medium bowl until tinted light green, about 2 minutes. Beat in sweetened condensed milk, then juice; set aside at room temperature to thicken.
For the crust, adjust oven rack to center position and heat oven to 325° F. Mix crumbs and sugar in medium bowl. Add butter; stir with fork until well-blended. Pour mixture into 9-inch pie pan; press crumbs over bottom and up sides of pan to form even crust. Bake until lightly browned and fragrant, about 15 minutes.
Transfer pan to wire rack; cool to room temperature, about 20 minutes.
Pour lime filling into crust; bake until center is set, yet wiggly when jiggled, 15 to 17 minutes.
Return pie to wire rack; cool to room temperature. Refrigerate until well-chilled, at least 3 hours. Can be covered with lightly oiled or oil-sprayed plastic wrap laid directly on filling and refrigerated up to 1 day.
For the whipped cream: up to 2 hours before serving, whip cream in medium bowl to very soft peaks. Adding confectioners' sugar 1 Tbsp at a time, continue whipping to just-stiff peaks. Decoratively pipe whipped cream over filling or spread evenly with rubber spatula. Garnish with optional sugared lime slices and serve.Makes 4 Source: