Sift the flour, baking powder and icing sugar into a bowl and make a well in the centre. Whisk the milk and egg together in a jug, then gradually beat into the flour mixture with a wooden spoon, drawing in the flour from the edges to make a batter the consistency of single cream.
Heat a non-stick frying pan and brush with a little of the oil. Pour 1 tbsp batter into the pan, swirl to make a 7cm circle, then repeat, leaving at least 3cm between each pancake. Once the tops start to bubble, turn the pancakes over and cook for a further 1-2 minutes until golden. Repeat until all the batter is used up – you should have about 12 pancakes.
To serve, put a pancake on each of 4 plates. Top with the banana slices and a generous spoonful of fromage frais. Repeat with 2 more pancakes to make a stack, then drizzle with the honey and sprinkle over the raisins.