This is just like the old fashioned banana pudding that my mom made on top of the stove. I've made this with Splenda and fat free wafers, mu husband likes it just as well.
I also have made meringue using Splenda and it works well also.
Place milk, sugar, egg yolks and flour in microwaveable bowl. Mix well. Microwave on high for 2 minutes, stir it well. Microwave for 2 more minutes, stir well. Keep an eye on it or it will boil over and make a mess. (At this point, I like to microwave a minute at the time to avoid this). As it starts to thicken, stir more often. After six minutes, or less, it should be getting thick, not too thick. If it is add milk by the tablespoon and stir to get it to a gravy consistency. It will thicken up as it cools. Add the butter and the vanilla extract. Stir well.
Put a layer of pudding in the bottom of your dish. Slice up enough bananas to cover. Then add a layer of vanilla wafers. Repeat with pudding; bananas; and wafers. I try to end with pudding on top.
Put the reserved egg whites in a clean grease-free bowl. Beat with mixer on medium high. When they start to get frothy, add 4 tablespoons of sugar and beat until glossy, stiff peaks form. Spread on top of pudding.
Broil in the oven until meringue is golden brown - DON'T TAKE YOUR EYES OFF IT WHILE IT IS BROILING, IT TAKES LESS THAN A MINUTE WITH A GAS RANGE!