Sift the flour, salt and caster sugar into a bowl. In a bowl, beat together the eggs and the egg yolk. Make a well in the centre of the flour mixture and add the eggs. Using a whisk or wooden spoon and starting in the centre, gradually mix the eggs with the flour, slowly adding the milk. Beat until you have a batter covered with bubbles. Cover and leave to stand in a cold place for at least 30 minutes.

Just before cooking the pancakes, stir in the melted butter (this makes all the difference to the flavour and texture and means you can cook them without greasing the pan each time).

Meanwhile, make the orange sauce. Put the butter, orange rind, icing sugar, Grand Marnier, if using, and orange juice into a pan and cook over a low heat until the butter has melted and the sugar has dissolved.

Place a non-stick crepe pan over a high heat and pour in a small ladleful of batter (enough to form a film in the base). When bubbles appear on the surface loosen the edges with a palette knife, flip over and cook briefly on the other side. Fold and slide on to a plate, spoon the warm sauce on top, sprinkle with orange rind and serve. Repeat with the remaining batter.