This rich pudding is good warm or cold.
In a saucepan, combine flour, egg yolks, sugar, and milk. Mix until smooth. Bring slowly to a boil and cook until thick and the consistency of pudding. Stir in vanilla. In a 2-quart casserole dish or in individual bowls, place a layer of vanilla wafers, a layer of thinly sliced bananas, and about half of the pudding. Repeat, working quickly. Top with whipped cream if desired.