Cheesy Broccoli & Cauliflower Gratin

Ingredients

• 300g broccoli florets
• 300g cauliflower florets
• 50g plain flour
• 600ml milk
• 50g butter
• 200g mature cheddar, grated (50g reserved for topping)
• 1 tsp Dijon mustard
• ¼ tsp ground nutmeg
• 75g fresh breadcrumbs
• pinch of black pepper
• 1 tsp sea salt
• 1 tbsp olive oil
• Rocket and seed salad, to serve
• Fresh parsley, to serve

Method

1. Heat the oven to 200°C fan. Bring a large pan of well-salted water to the boil and blanch the broccoli and cauliflower florets for 4–5 minutes until just tender with a little bite. Drain thoroughly and leave to steam-dry in the colander — any lingering water will thin the sauce later.
2. Melt the butter in a saucepan over a medium heat until foaming, then stir in the flour. Cook for 1–2 minutes, stirring constantly, until the roux smells nutty and biscuity but hasn't taken on colour.
3. Gradually whisk in the milk a splash at a time, letting each addition come together before adding the next, until you have a smooth, lump-free sauce. Bring to a gentle simmer and cook for 3–4 minutes, stirring, until thick enough to coat the back of a spoon.
4. Off the heat, stir in the Dijon, nutmeg and 150g of the cheddar until the sauce is glossy and molten. Season generously with salt and black pepper.
5. Fold the drained florets through the cheese sauce so every nook is coated, then tip into a shallow ovenproof dish, nudging the veg into an even layer.
6. Toss the breadcrumbs with the reserved 50g cheddar and the olive oil, season with the sea salt and a pinch of pepper, then scatter evenly over the top.
7. Bake for 20–25 minutes until the sauce is bubbling fiercely at the edges and the topping is deep golden and crunchy.
8. Rest for 5 minutes so the sauce settles, then finish with a squeeze of lemon and a scattering of fresh herbs before serving hot.