1. Sift together the flour, sugar, and salt. Whisk in the evaporated milk until the dry ingredients are dissolved.
2. Place in a double boiler over simmering water. (The custard can also be prepared in a heavy-bottomed saucepan over very low heat, stirring constantly, to prevent scorching.)
3. Whisk 4 egg yolks and 1 whole egg with 2 cups of whole milk.
4. Add to the ingredients in the double boiler whisking until fully combined. Continue to stir for 12-15 minutes or until the custard has thickened. Remove from the heat.
5. Stir in 1 tablespoon of butter and 1 teaspoon of pure vanilla extract.
6. To assemble, divide the vanilla wafers, setting aside 18 to line the edge of the dish.
7. In a 2 quart oven-safe dish, alternate layers of vanilla wafers, sliced bananas, and custard.
8. Line the edge of the dish with the reserved 18 vanilla wafers and set aside.
To prepare the meringue:
1. Whip together 4 egg whites, 1 teaspoon pure vanilla extract and ½ teaspoon cream of tartar.
2. Slowly whip in ¼ cup granulated sugar.
3. Whip the egg whites until stiff peaks form.
4. Spread the meringue evenly over the top of the banana pudding.
5. Preheat the oven to broil. Place the banana pudding under the broiler. Carefully turn the banana pudding as required for even browning. Continue this process until the top is golden. Chill for 4 hours before serving.