Salt a pot of water and bring to the boil. Slice the onion, cook for a few minutes, then add the spinach with roots removed.

Drain the vegetables, then soak in cold water to cool. When cooled, drain again, press out any water, and chop into small pieces.

Add the chopped, cooked onions and spinach to a blender.

Add just enough milk to cover the vegetables and purée until smooth.

Add the rest of the milk and purée again.

Transfer to a pot and turn on the heat. Add the stock cube/granules and dissolve.

Bring to a simmer and add the grated cheese. Taste and adjust the seasoning with Krazy Salt (or salt) and pepper.

Serve in a mug.