Ficelle picarde - mushroom and ham crepes au gratin

To prepare crepe batter

1. Place the egg, flour and salt in a bowl and mix together into a paste - don't worry if it's not fully combined, you more want to break the egg up.
2. Gradually add the milk and whisk until the batter is smooth, then set aside. Alternatively, you can mix everything in a blender. Either way, it's best to let the batter rest around 20-30 minutes to hydrate - you can prepare the mushrooms in the meantime.

For mushroom duxelles

1. Finley chop the shallot and dice the mushrooms into a small dice. Crush or finely chop the garlic, if using.
2. Warm the butter in a wide skillet/frying pan over a medium heat then add the shallots. Cook to soften, stirring now and then. Add the garlic after a minute, if using, and cook until soft but not browning.
3. Add the mushrooms and cook, stirring regularly, so that the mushrooms soften. They will initially release liquid as they soften, but keep cooking and they will then evaporate the liquid.
4. When there is no more liquid in the skillet, add the white wine and stir so that it mixes and is absorbed or evaporates. Once there is no more liquid, remove from the heat and set aside.

To cook crepes and assemble

1. When ready to cook crepes, melt a little butter on a crepe pan and when hot, pour some of the batter on to the pan and quickly swirl so that the batter spreads into a thin layer, filling the pan. (If you have proper crepe-making tools you can use these, but this is the method if you don't.)
2. Let the crepe cook until dry on top and edges starting to curl slightly then carefully flip over with a spatula. Cook on other side until you have light brown spots, then remove and repeat with rest of batter. You should get two large or three small er crepes, depending on the size of your pan.
3. Preheat the oven to 400F/200C.
4. Place a slice of ham on top of each crepe then a line of the mushroom mixture on top, slightly to one side. On the side with the mushrooms closest, roll up the crepe with the fillings inside. You want it tight enough to hold together, but not so that the filling spills out.
5. Repeat with the rest of the crepes then place them in an ovenproof dish. Scatter the grated cheese over the top of the crepes, covering them fairly evenly, then bake in the pre-heated oven for around 5 - 7 minutes until the cheese has melted and the edges of the crepes are just starting to brown.