Combine flour and salt in a medium saucepan. Slowly stir in milks and yolks, then cook over medium heat, stirring constantly for 8 minutes or until thickened. Remove from heat, then add vanilla extract.
Arrange 1 cup banana slices in a 2-quart baking dish. Spoon 1/3 pudding mixture over bananas; cover with 15 vanilla wafers. Repeat, then top with a third layer of pudding. Arrange remaining 15 wafers around inside edge of dish; gently push into pudding.
Preheat oven to 325°. Beat egg whites at high speed with an electric mixer until foamy. Add sugar 1 Tbsp. at a time, beating until stiff peaks form and sugar dissolves, for 2 to 4 minutes. Spread meringue over pudding. Bake for 25 minutes or until golden. Let cool for at least 30 minutes.