1. Preheat the oven to 375 degrees.
2. Combine the oats, flour, salt, and sugar in a bowl.
3. Lightly beat the egg yolks and stir in the hot milk. Beat until very light and thick. Beat in the oil, vanilla, and mashed banana. Sprinkle the dry ingredients over the yolk mixture and fold in gently.
4. Beat the egg whites until stiff but not dry and fold into the batter. Spoon into oiled muffin tins until they are two-thirds full.
5. Bake for 30 minutes, or until golden and done. Cool on a rack.