Step 1

Preheat the oven to 220ºC, gas mark 7. Break the head of the cauliflower into florets, cutting any larger pieces in half. Reserve the stem and leaves to use later (see tips). Place the florets into a large roasting dish and drizzle with the oil. Season lightly, then bake for 20 minutes, until golden but not completely cooked through. Finely dice the cauliflower stalk and set aside.

Step 2

Meanwhile, make the cheese sauce. Melt the butter in a medium saucepan and cook over a low heat for 4-5 minutes until the butter is foamy and the milk solids have turned brown and smell nutty. Add the garlic and diced cauliflower stalk and cook for 1-2 minutes, until the garlic is golden. Stir in the flour and cook for a few minutes more to form a paste.

Step 3

Pour in the milk a little at a time, whisking constantly, to form a smooth, thick sauce. Add the mustard, a pinch of finely grated nutmeg, and three-quarters of the Cheddar and Cheshire cheeses. Mix well until completely melted.

Step 4

Tip the roasted cauliflower into a 2L baking dish and pour the sauce over the top. Stir well so each floret is coated. Sprinkle over the remaining cheese. At this point, you can cool, then cover the cauliflower cheese and refrigerate for up to 3 days, or freeze for up to 3 months (see tips).

Step 5

Using a mini food processor or sharp knife, finely chop the croutons, sage and parmesan together to make a crumbly topping. When ready to cook, preheat the oven to 200ºC, gas mark 6. Sprinkle the top with the crumbs, then bake for 25-30 minutes, or until bubbling and golden. Serve piping hot, garnished with a few whole sage leaves, if liked.