Peel and finely chop the onion. Halve the swede. Peel one half. Finely chop the swede into a small dice, around 1 cm across. Trim the bottom off the chard. Rinse the leaves. Finely slice the stems and leaves.
Warm 2 tsp olive oil in a pan over a medium heat. Add the chicken. Fry for 5 mins till the chicken is golden. Turn every so often till it’s evenly coloured. Lift the chicken out of the pan. Pop on a plate. Put to one side.
Add the onion, swede and chard stems to the pan. Season and add a splash of water. Cover the veg with greaseproof paper. Pop on the lid. Sweat the veg over a very low heat for 10 mins till they are soft.
Fill the kettle and boil it. Crumble the stock cube into the pan. Pour in 600ml hot water from the kettle. Return the chicken to the pan. Cover. Bring to the boil. Boil for 10 mins till the chicken is cooked through.
Measure out 3 tbsp of the sweetcorn and add to the pan. Pour in 250ml of the milk. Gently heat for 2-3 mins to warm through.
Ladle half the soup into a blender or food processor. Blitz till smooth. Pour back into the pan. Or leave the soup chunky if you don’t have a blender or processor.
Measure out another 3 tbsp of the sweetcorn and add to the pan. Add the chard leaves to the pan. Gently heat for 2-3 mins to warm everything through.
Rinse the parsley. Pat dry with kitchen paper. Roughly chop the leaves. Ladle the chowder into bowls. Top with the chopped parsley to serve.