Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, 1 1/4c sugar, and salt in a large sauce pan; stir with a whisk. Gradually add milk; stir until smooth. Scrape seeds from vanilla bean; add seeds and bean to milk mixture.
Cook over medium heat 12 minutes or until thick and bubbly, stirring constantly.
Place eggs in a large bowl, if using vanilla extract beat it in with the eggs, gradually add hot milk mixture, stirring constantly. Place mixture in pan; cook over medium heat 2 minutes or until thick and bubbly, stirring constantly. Discard vanilla bean.
Place egg whites in a large bowl; beat with a mixer at high speed until foamy. Add 3/4 cup sugar, 1 tablespoon at a time, until stiff peaks form.
Arrange half of vanilla wafers in the bottom of a 13 x 9" baking dish. Arrange half of banana slices over wafers. Pour half of custard over banana. Repeat procedure with remaining wafers, banana, and custard.
Top with meringue, spread evenly to edge of dish.
Bake at 325* for 20 minutes or until lightly browned. Serve pudding warm or chilled.
Serving size 3/4 cup; 289 calories; 16% from fat
Very good and very sweet for a low fat low calorie dish.