Sift the flour into a large bowl and add the salt. Make a well in the centre of the flour and break in the eggs. Slowly incorporate the eggs into the flour, whisking them in from the centre and gradually working outwards. Once combined, whisk vigorously to get rid of lumps and you have a thick batter. Add the milk and mix well. Melt the 30g butter, add the mixture and then leave to rest for at 30 minutes to an hour.
Prepare a roux: melt the butter in a saucepan and then add the flour and mix well. Cook for 5 minutes, stirring all the time and without allowing the mixture to brown. Allow to cool.
Bring the milk to the boil and, once the roux has called, add the milk to the roux and whisk together. Return the mixture to the heat and cook for 5 to 10 minutes over a low heat until thick. Season with salt, pepper and grated nutmeg and remove from the heat. Finish the sauce by whisking in the eggs yolks and the emmental.
Wash and finely chop the chives. Brush the mushrooms clean and thinly slice. Peel and thinly slice the shallots. Mix these chopped ingredients into the sauce and keep warm while you cook the pancakes.
Heat a non-stick frying pan and add a little butter or oil. Add a ladleful of batter to the pan and tilt to spread the mixture out. Cook until golden brown underneath and then turn over and cook on the other side. Remove from the pan and add a generous amount of the mushroom mixture. Roll the pancake and serve immediately.
«Vary the filling of your pancakes according to taste... try adding ham or chorizo and serve with a fresh green salad.»