Place a medium sized pan over a moderate heat and add the oil. Once hot, add the leek slices and fry for a couple of minutes until softened, stirring occasionally.

Add the butter followed by the mushrooms, garlic (if using) and a pinch of salt. Fry for three minutes or until the mushrooms have cooked through, stirring occasionally.

Add the butter beans and stir through. If the mixture looks dry, add a splash of water.

Add the tamari and greens, place the lid on the pan and allow the greens to wilt for about three minutes.

Add the cream, stir well and replace the lid. Allow the mixture to bubble for a minute or two, then remove from the heat.

Grate in the nutmeg, grind in the pepper and stir in the lemon juice. Taste and add more salt if needed.

Pour the contents of the pan into a dish and scatter the parsley over the top.