Warm your oven to 200C/Fan 180C/Gas 6. Fill up your kettle and boil it. Pour the hot water into a large pan and add a good pinch of salt. Pop the pan onto the hob and return to the boil. Trim the base off the cauliflower. Discard any tatty leaves, and roughly chop the others into small pieces. Chop the cauliflower into small florets. Slice the stalk into small chunks.

Add the chopped cauliflower and leaves to the boiling water and simmer for 5-8 mins, till just tender. When the cauliflower is cooked, drain well through a colander.

Peel and finely chop the onion. Peel and thinly slice the garlic cloves. Coarsely grate the cheddar.

Pop the empty, dry pan you used to cook the cauliflower back onto a medium heat. Add the butter to the pan and melt, then add the chopped onion and garlic. Cook for 5-6 mins, stirring occasionally, till softened.

Stir 2 tbsp cornflour into the veg and stir well. Cook for 2 mins, till the cornflour mixes with the butter and forms a sandy texture. Slowly pour in 400ml milk, stirring frequently as you pour, till the milk forms a smooth thick sauce. Warm the sauce to a simmer, then stir in the grated cheese. Stir till melted, then fold in the cooked cauliflower.

Transfer the cauliflower and sauce to an ovenproof dish and season with freshly ground pepper. Slide the dish into the warm oven and bake for 25-30 mins till golden on top and bubbling at the side. Serve as part of your Christmas roast.