Position rack in middle of oven. Preheat oven to 350 degrees.
Place graham crackers and light brown sugar in a food processor, process into crumbs (or smash into crumbs in a sealed plastic bag using a rolling pin)
Spoon crumbs into small bowl; add melted butter and combine with fingers into a coarse meal.
Distribute crumbs evenly on bottom and up sides of an ungreased 9 inch pie plate.
Chill for 30 minutes fefore baking. Bake until crust starts to turn golden, about 8-10 minutes. Remove from oven and let cool.
Meanwhile, in a large bowl, using an electric mixer, whip egg whites until frothy; foldn in egg, dark brown sugar, salt, pumpkin pie spice, canned pumpkin and evaporated milk. Beat pumpkin custard until smooth and pour into pie shell. Bake until a knife inserted in center comes out clean. About 45-55 minutes.
Slice into 8 pieces. Top each piece with 1/2 tablespoon of whipped topping and serve warm or at room temperature.