Separate the eggs, putting the whites into one bowl and the yolks into another. Combine the plain flour, baking powder and milk with the egg yolks and mix until it forms a smooth, thick batter. Whisk the whites with the salt until they form stiff peaks. Fold the whites into the batter – it is now ready to use. Heat a non-stick frying pan over a moderate heat.
Pour some of your batter into the pan and fry for a couple of minutes until it starts to look golden and firm. Loosen with a spatula and turn or flip the pancake over. Continue frying until golden. Melt the butter and sugar in a separate pan over a low heat until they form a caramel sauce – about 3 minutes.
Peel and cut the bananas lengthways, add them to the pan and cook gently until they are golden, turning after a few minutes. You might need to alter the cooking time slightly, depending on how ripe your bananas are. Serve them on the pancakes topped with a good spoonful of crème fraîche.