Whisk the eggs and sugar together in a large bowl and then add the milk. Sift the flour into the egg mixture, whisking continuously until the batter is the consistency of thick cream.
Melt the butter in a small saucepan, then add 1 tablespoon to the crepe batter, along with a pinch of salt.
Heat a non-stick frying pan over medium heat, then add enough of the melted butter to coat the base of the pan. Add a ladleful of crepe batter, turning the pan to coat the base completely. Cook the batter for 1 minute or until you see the edges of the crêpe beginning to crisp and loosen from the sides and the base of the crepe is light golden. Turnover and cook for another 10–15 seconds. Transfer to a plate and keep warm. Repeat with the remaining melted butter and crepe batter, stacking the crepes on top of each other as you go. the batter makes 12 crepes in total.
To make the orange sauce, juice the oranges and cut the rind into julienne. Strain the orange juice into a jug; you should have 250 ml. Combine the orange rind and the sugar on a bowl and rub them together with your fingertips.
Place the sugar into the warm frying pan, then cook over medium heat until the sugar melts and turns golden. Add the orange juice and stir to melt the sugar. Add the butter and shake the pan until it is combined with the orange sauce. Add a crepe to the pan and fold it into thirds, spooning over the sauce. Repeat with another 5 crepes. Add the Cointreau and Cognac to the pan, moving the pan off the heat to flambé.
Transfer the crepes to a serving plate, then pour over the sauce.