1. In a bowl, whisk the eggs with the sugar and vanilla until fluffy. Gradually add the milk and finally the flour, stirring continuously until you have a smooth, thin batter.
2. Let the mixture rest for 30 minutes. Lightly grease a non-stick pan with butter and pour in a little batter.
3. Cook the crêpe for 1 minute on each side and continue until all the batter is used up.
For the flambé:
1. In a pan, melt the butter, add the sugar and orange juice, and let the sauce thicken slightly.
2. Add the cognac, heat it up, and carefully light it to flambé. Place the folded crêpes into the sauce, spoon some sauce over them, and let them soak up the aromas.
3. Serve hot, with a little sauce on top and some orange zest.