Preheat the oven to 180C fan/gas mark 6.
Steam the cauliflower over boiling water for 5 minutes, until just softening. Remove and leave aside to cool slightly.
Put the butter into a 24cm round casserole pan or ovenproof dish of a similar size and place on a medium heat.
Add the onion and sauté for 8 minutes, until soft and golden.
Add the cumin seeds, curry powder, mustard powder and chillies and cook for 4 minutes, stirring occasionally.
Add the mustard seeds, cook for another minute, then pour in the cream.
Add 100g of cheddar and ½ teaspoon of salt, and simmer for 2-3 minutes, for the sauce to slightly thicken.
Add the cauliflower, stir gently, and simmer for another minute before removing from the heat.
Place the remaining 20g of cheddar in a bowl and add the breadcrumbs and parsley. Mix, then sprinkle over the cauliflower.
Wipe the top inside edge of the pan clean (with a spatula or cloth) – any cream there will burn – and place in the oven.
Bake for 8 minutes, until the sauce is bubbling and the cauliflower is hot.
Turn the grill to high and keep the pan underneath for 4 minutes, or until the top is golden and crisp. Keep an eye on it so that it does not burn.
Remove from the grill and allow to cool a little – just for 5 minutes or so – before serving.
