Mix the flour and salt in a bowl, create a well in the middle. Whisk together the milk, water, eggs and butter. Gradually pour the liquid into the well while stirring with a whisk, continue to whisk until the batter is smooth. Cover and leave to stand at room temperature for approx. 30 mins.
To cook the crêpes
Heat a little clarified butter in a non-stick frying pan. Pour enough batter into the pan to thinly cover the base. Reduce the heat. Once the underside is cooked and separates from the pan, turn the crêpe, finish cooking, cover and keep warm. Repeat these steps with the remaining batter.
Boil the sugar and water in a wide pan without stirring. Reduce the heat and simmer, swirling the pan occasionally until a light brown caramel has formed. Remove the pan from the heat, add the butter, orange zest and juice along with the liqueur, reduce to a syrupy consistency. Add the crêpes one after the other, fold each twice. Top with the orange segments, pour the cognac over the top, flambée (with the extractor fan turned off).