Whisk together the flour, 20 g/3⁄4 oz of the sugar, the egg and milk for 5 minutes.
You should now have a batter mixture.
Test it by dipping a spoon in and seeing if it coats the back of the spoon evenly.
Heat a little sunflower oil in a frying pan and leave to smoke, then pour half a cup of the batter in the middle of the pan, tilt the pan to move the batter to the edges and replace on the heat for 3 minutes.
Turn the pancake over with a spatula and fry for another 2 minutes.
Remove from the pan and put on a plate to cool.
Repeat with the rest of the batter.
To make the filling, drop the butter into the frying pan, add the bananas and cook for 1 minute.
Add the rum and flambé until the flames die down.
Cook for a further 2 minutes and leave to the side.
Whisk up the cream with the remaining sugar and spoon a little into the middle of each pancake.
Top with the bananas, roll up and serve on a pool of pouring cream, if so desired – watch those waistlines!