Heat your oven to 200°C/Fan 180°C/Gas 6. Fill a large pan with water and add a pinch of salt. Pop on a lid and bring to the boil.

Peel the onion and thinly slice it. Peel the garlic and crush or finely grate it. Grate the cheddar. Drain the mozzarella and tear it into small pieces. Pop both cheeses into a bowl.

Pour 1 tbsp olive oil into a pan and warm it on a medium heat. Add the onion and garlic with a pinch of salt and pepper and fry for 5 mins, stirring occasionally, till softened.

While the onion and garlic cook, trim the base off the cauliflower. Break off and reserve the leaves. Cut the cauliflower into 6 large wedges.

The water in the pan should be boiling. Tip in the pasta and the cauliflower wedges and leaves. Simmer for 8 mins, then drain.

Sprinkle the flour into the onion pan, stir well and fry for 2 mins. Whisk in 1 tbsp mustard and around 100ml of the milk, scraping the bottom of the pan, till the onions thicken into a paste. Slowly pour in the rest of the milk, continuously whisking, till combined. Bring to a simmer, then stir in the cheddar and mozzarella.

Tip the pasta and cauliflower into a large ovenproof pan or casserole dish. Pour over the cheese sauce and give everything a stir to coat. Season with a pinch of black pepper. Slide into the oven and bake for 20 mins, till bubbling and golden brown at the edges.

While the cauliflower mac and cheese is baking, slice the kale leaves off their cores and roughly shred them. Pour 1 tbsp olive oil into a frying pan and warm it to a medium-high heat. Add the kale with 3 tbsp water and a little salt and pepper. Stir fry for 4-5 mins, till tender. Squeeze in the juice from the lemon and stir well.

Serve the cauliflower mac and cheese on a couple of warm plates, with the lemony kale on the side.