To prepare filling. Whisk together first 5 ingredients in a saucepan. Cook over medium to low heat whisking constantly for 8-10 minutes or until pudding thickens. (Mixture will begin to bubble and will form soft peaks when whisk is lifted) Remove from heat and stir in vanilla. Use immediately.
Preheat oven to 350 degrees. Arrange half of banana slices over bottom of crust. Spread 3/4 of prepared filling over bananas. Top with vanilla wafers and remaining bananas. Spread remaining filling on top. Beat egg whites at high speed until foamy. Add sugar 1 Tbs at a time until peaks form. Spread over pie evenly sealing edges. Bake for 10-12 minutes or until golden brown. Remove from oven and cool 1 hour on a wire rack. Coarsely crush 10 vanilla wafers and sprinkle for garnish. Chill for 4 hours.