Mix crumbs, sugar, and melted butter; press into a 9-inch pie plate. Freeze for 15 mins.
Whisk condensed milk, sour cream, lime juice, and zest in a large bowl.
In another bowl, beat heavy cream and powdered sugar to stiff peaks.
Gently fold half the whipped cream into the lime mixture.
Pour into the crust and smooth the top.
Refrigerate for 4 hours or overnight.
Top with remaining whipped cream and zest before serving.