Preheat the oven to 185℃

Break the cauliflower and the broccoli into florets. Cut any extra-large ones in half so that they are all roughly the same size.

Bring a saucepan of water to the boil, place the broccoli in and cook for 4-5 minutes. Drain, then place the broccoli along with the cauliflower into a roasting tray.

To make the cheese sauce, add the milk, flour and butter into a saucepan and cook over a medium-high heat.

Keep whisking fast as the butter melts and the mixture comes to the boil. The flour will disappear, and the sauce will begin to thicken.

Whisk for two minutes while the sauce bubbles and becomes nice and thick.

Turn off the heat, then add the grated cheddar and grated parmesan. Whisk until it's all melted.

Add the ground nutmeg and the mustard powder and mix well.

Pour the cheese sauce all over the cauliflower and the broccoli.

Scatter the cheddar and the parmesan over the top, followed by the chopped thyme, flaked almonds and stale breadcrumbs.

Bake in the oven for 50 minutes. Leave to stand at room temperature for at least ten minutes before serving.