1. Preheat the oven to 220°C/200°C fan/Gas 7 and butter the ramekins generously. Lay a piece of kitchen paper in the base of a roasting tin – the paper stops the ramekins slipping in the tin.

2. Melt 25g (1oz) of the butter in a large, non-stick frying pan, add the mushrooms and fry them over a high heat for a few minutes. Cover the pan with a lid, lower the heat and cook for another 4 minutes, then remove the lid and fry over a high heat to evaporate the liquid. Remove the mushrooms with a slotted spoon and set them aside.

3. To make the soufflé base, melt the remaining butter in a saucepan. Whisk in the flour to make a roux and cook for a minute. Gradually add the hot milk and whisk over a high heat until you have a thickened, smooth sauce.

4. Remove the pan from the heat and beat in the egg yolks, one at a time, until the sauce is smooth. Add the mushrooms and the cheese and season, then set aside to cool a little.

5. Whisk the egg whites until soft peaks form. Stir about a tablespoon of egg whites into the egg and mushroom mixture and carefully fold the rest of it in, keeping everything light and airy.

6. Divide the soufflé mixture evenly between the ramekins and sit them on the paper in the roasting tin. Pour enough boiling water into the tin to come halfway up the sides of the ramekins. Bake the soufflés for about 15 minutes until risen and lightly golden.

7. To make the sauce, pour the cream into a jug and add the spinach and mustard. Season with salt and pepper and stir to combine.

8. To serve, preheat the oven to 220°C/200°C fan/Gas 7. Carefully run a knife around the edge of each ramekin and remove the soufflés. Sit the soufflés, browned side up, in an ovenproof dish, then spoon the sauce around them. Reheat for about 12 minutes until piping hot. Serve with dressed leaves or some brown bread.

Prepare ahead: Can be made up to 8 hours ahead and reheated with the sauce as in step 8.