Combine cookie crumbs and butter in an 8-inch pie plate. Mix well and press firmly in an even layer over the bottom and sides of pan to form a crust. Place in freezer until firm.

Meanwhile, melt marshmallows with milk and salt over hot water. Cool until mixture will mound on a spoon. Stir in Kahlua.

Beat whipping cream stiff and gently fold into marshmallow mixture. Chill in fridge about 30 minutes, until mixture holds ripples when stirred lightly. Turn into chilled cookie shell and freeze firm.

(Optional) Before serving, sprinkle some additional cookie crumbs on top.

Cut into wedges.