For the crust: Preheat oven to 350° F. Butter a 9-inch pie pan.
Break up into crumbs in food processor or place crackers in a large plastic bag and crush with a rolling pin. Add melted butter and sugar and stir. Press crumb mixture into pan forming a neat border around the edge. Bake until set and golden, about 8 minutes, and set aside. Keep oven on.
For the filling: In an electric mixer with a wire whisk attachment, beat the egg yolks and lime zest at high speed until very fluffy, about 5 minutes, Gradually add the condensed milk and continue to beat until thick, 3 or 4 minutes longer. Lower the mixer speed and slowly add the lime juice, mixing until combined, no longer. Pour mixture into the crust. Bake for 10 minutes or until filling has just set. Cool on a wire rack, then refrigerate, Freeze for 15 to 20 minutes before serving.
For the topping: Whip the cream and confectioners sugar until nearly stiff. Cut the pie into wedges and serve very cold. Top each wedge with dollop of whipped cream.Makes 4 to 6 Source: