Place the sifted flour, salt, egg and milk in a food processor. Process until the mixture is smooth. Transfer into a jug / bowl and refrigerate for 30 minutes.
Banana and chocolate filling:
Melt the salted butter and the 1 tablespoon sugar in a frying pan over medium heat. Add in the sliced bananas and let them cook gently for 3 minutes, turning the bananas frequently.
Lower the heat to low. Add in the brandy / rum and be careful not to let the alcohol ignite in the pan. Let the bananas and alcohol simmer for 2 minutes. The bananas will be soft and the liquid will be syrupy. Remove the frying pan from heat and set it aside.
Cooking the crêpes:
Melt a little butter in a frying pan. For a 7-inch frying pan, pour 60 ml of the batter into the frying pan. For a 9-inch frying pan, pour 100 ml of the batter into the frying pan.
Tilt the frying pan around so the batter coats the base. Cook for 2 minutes over medium to low heat until golden brown underneath.
Using a palette knife (using tongs may break the crêpe, so a palette knife works best here), slide it underneath the crêpe to loosen it. Turn it over and cook for an additional 1 minute.
Transfer the crêpe to a plate, and cover with a piece of greaseproof paper. Repeat with the remaining batter, adding more butter if necessary and stack the crêpes up, with a piece of greaseproof paper in between each crêpe.
Making the boozy sauce and assembly:Divide the bananas and chopped chocolate among the crêpes. Fold the crêpes into quarters.
Melt the 100 grams butter and 100 grams sugar in a frying pan over medium heat. Lower the heat to low and add in the brandy / rum and be careful not to let the alcohol ignite in the pan. Stir the mixture.
Slide the folded crêpes into the frying pan. Cook for 1 minute. Turn the crêpes over and cook for another 1 minute to melt the chocolate. Transfer the crêpes onto serving plates. Drizzle with extra sauce and dust with icing sugar. Serve immediately.