To prepare the pancakes, sift the ﬂour and salt into a bowl. Make a well in the centre, add the egg and gradually whisk in the milk until the batter is smooth. Pour into a measuring jug and set aside for at least 30 minutes while you prepare the sauce and filling.
To prepare the sauce, add the bouquet garni and onion to the milk and bring to the boil. Remove from the heat, cover and stand for 30 minutes to infuse the flavours.
Meanwhile, prepare the filling. Melt the butter in a medium saucepan, add the onion and cook until soft. Add the mushrooms and sherry, cover and cook for 30 minutes, stirring occasionally. Uncover and cook for a further 15 minutes, or until most of the liquid has evaporated. Remove the pan from the heat, season the ﬁlling to taste, cover and set aside.
To cook the pancakes, heat 1 teaspoon of the oil in an 18-cm nonstick frying pan until a faint haze is given off. Stir the batter and pour in one-eighth. Tilt the pan so that it coats the base evenly, then cook over medium heat for 1–2 minutes, or until the underside is golden. Turn the pancake over and cook the second side for a minute more. Tip the pancake onto a plate and cover with a sheet of greaseproof paper.
Make seven more pancakes in this way, interleaving them with greaseproof paper.
Preheat the oven to 200°C. Lightly oil a shallow ovenproof dish.
To finish off the sauce, melt the butter in a medium saucepan, stir in the ﬂour and cook over medium heat for 1 minute. Strain the infused milk and gradually add to the pan, stirring continuously until the sauce comes to the boil and thickens. Reduce the heat and cook for 2–3 minutes. Remove from the heat, season to taste and stir in the chopped chervil or parsley.
Spoon some of the mushroom mixture onto the centre of each pancake, roll up and place, folded side down, in the baking dish. Pour the sauce over the rolls, sprinkle with cheese and cook in the centre of the oven for 35–40 minutes, or until golden brown and bubbling.
SEAFOOD PANCAKES • You can also prepare a seafood filling by combining 500 g small, cooked, shelled prawns, 200 g cooked crabmeat, 1/4 cup finely chopped spring onion, the grated rind of 1 lemon and a dash of Tabasco sauce. Season to taste, cover and set aside. • Before filling the rolls, mix 1/4 cup of the sauce into the seafood. Place the rolls in an ovenproof dish and pour the rest of the sauce over them. • Sprinkle the rolls with cheese and cook as for mushroom pancakes.