For the pancake batter
15 g butter (salted)
150 g plain flour
200 ml milk
For the filling
25 g butter
1 onion, finely chopped
400 g baby spinach
225 g mushrooms, sliced
100 ml single cream
1 tsp parsley, freshly chopped
chives, chopped, to garnish (optional)
For the pancake batter: Melt the butter over a low heat. Put the flour, a pinch of salt, milk, eggs and 2 tablespoons of water into a mixing bowl and beat together with a hand whisk to make a smooth batter. Whisk in the melted butter and leave to rest for 20-30 minutes.
For the filling: Melt the butter in a heavy saucepan until it foams. Add the onion, then cover and sweat over a gentle heat for 5-10 minutes, until soft but not coloured. Meanwhile, cook the spinach in a tiny amount of water in a large lidded saucepan for about 3-4 minutes or until the leaves wilt. Drain the spinach, then squeeze out the excess liquid with the back of a spoon.
Add the mushrooms to the onion and cook for a few more minutes, then stir in the cream, parsley and spinach. Season with a squeeze of lemon juice, salt and pepper.
Cook ladles of the pancake batter into a non-stick frying pan until set on the surface. Turn over to cook the other side. Use to make 4 large or 8 small pancakes.
Lay the pancakes on warm plates and spoon the filling in the middle and fold over. Serve, sprinkled with chopped chives.