You will need
Heat the butter with the oil in a heavy-based saucepan. Add the onion and celery and fry gently for about 5 minutes until soft but not coloured.
Add the potatoes and fry for a few more minutes, tossing to mix them with the onion and celery. Pour in the milk and stock and bring to the bowl, stirring.
Add the herbs and salt and pepper to taste, then lower the heat, cover and simmer for about 20 minutes until the potatoes are tender
Add the ham, sweetcorn and pepper and cook for a further 5 minutes until heated through
Pour into flameproof bowls, then sprinkle with the cheese. Flash under a preheated grill until golden and bubbling.
cooking for one or two