Cauliflower Cheese Gratin

Heat the oven to 200°C (fan 180°C or 400°F). Bring a large pot of water to a boil and season heavily with salt — it should taste like mild seawater. Grate the Gruyère and Parmesan, measure the flour and butter, and warm the milk in a small saucepan until steaming but not simmering.

Add the cauliflower florets to the boiling water and blanch for 5-6 minutes, until just tender with a little resistance at the core — they will continue to cook in the oven. Drain thoroughly in a colander and leave to steam-dry for 5 minutes.

Melt the butter in a heavy-bottomed saucepan over medium heat. Add the flour and whisk constantly for 2 minutes until the roux turns a pale straw colour and smells faintly nutty.

Remove the pan from the heat and add the warm milk in a slow, steady stream, whisking vigorously to prevent lumps. Return to medium heat and whisk continuously for 6-8 minutes until the béchamel is thick enough to coat the back of a spoon.

Remove from the heat and stir in the Dijon mustard, nutmeg, white pepper, and two-thirds of the Gruyère. Season with salt to taste and stir until the cheese is fully melted and the sauce is smooth.

Arrange the drained cauliflower florets in a single, snug layer in a 30cm oval or equivalent gratin dish. Pour the cheese béchamel evenly over the cauliflower, nudging the sauce between the florets with a spoon.

Combine the remaining Gruyère, all of the Parmesan, and the breadcrumbs in a small bowl, then scatter the mixture evenly over the surface.

Bake on the middle rack for 25-30 minutes until the top is deeply golden and the sauce is visibly bubbling at the edges. If the top needs more colour, switch to the grill for the final 2-3 minutes.

Rest for 5 minutes before serving so the sauce settles and thickens slightly.