For the crêpe, place the flour, eggs, two tablespoons of the vegetable oil and caster sugar together into a bowl and whisk together to make a thick paste.
Gradually whisk in the milk, until a smooth batter forms.
Heat the remaining one tablespoon of oil in a shallow frying pan. Place the slices of banana onto the base of the pan, then pour over enough batter to cover in a thin layer. Cook for 2-3 minutes, until golden-brown on base, then carefully turn over and cook for a further minute, until golden-brown on the other side.
For the chocolate sauce, place chocolate pieces in a bowl. Add the boiling water and whisk until the chocolate has melted.
Add the pecans and stir well.
To serve, place the crepe onto a plate and pour chocolate pecan sauce over. Drizzle with double cream and serve.