Step 1 Mix all the batter ingredients until smooth and leave to rest for at least half an hour or over night in the fridge. Pre-heat a 28cm non-stick shallow frying pan. Add in a drizzle of veg oil.
Step 2 Whilst tipping the hot frying pan at a slight angle, and starting at the top edge, ladle in enough batter to just coat the bottom of the pan. The crêpe should be thin and if the pan is good and hot the batter will bubble up and make lots of little holes, allowing it to go nice and crisp. After a couple of minutes turn the crêpe over and allow it to cook on the second side.
Step 3 Now crack your egg on to the crêpe, use a spatula to pull the egg white over the surface of the crêpe to allow it to cook.
Step 4 Scatter on the ham and cheese and allow it to melt a little before folding in the edges to make a square with the golden yolk sitting proudly in the middle. Serve immediately with a turn of black pepper and a green salad.
If you have several hungry mouths to feed then you can cook the galettes in advance keeping them separated with baking parchment. Finish them as before with a little knob of butter in the pan. I must warn you that one is never enough, so the above recipe will likely only feed four.