- 250g (9oz) macaroni
- 1 cauliflower, broken into florets
- 1 broccoli, broken into florets
- 700ml (1¼ pints) cold milk
- 50g (2oz) butter, plus extra for greasing
- 50g (2oz) plain flour
- 1 tsp wholegrain mustard
- Pinch of nutmeg
- 200g (7oz) Cheddar cheese, grated
Donal says: "At one of my recent cookery demonstrations I got a great tip to make an all-in-one white sauce, which simplifies the process here. There are two things that are key to this method: the milk must be cold when you start, and remember to keep whisking vigorously until the sauce thickens.
"If you want to take this simple recipe one step further, add some fried smoked streaky bacon bits. This is a great dish for a leftovers lunchbox the next day."
- Fill a large cooking pot (big enough to hold the cooked pasta, broccoli and cauliflower) with water and bring to the boil over a high heat. Add the macaroni and cook until al dente, for about 12 minutes.
- Five minutes before the pasta is cooked, add the cauliflower florets to the water. Two minutes later, add the broccoli florets. (If you don't have enough space, just put on a second pot of boiling water.) Cook for the remaining 3 minutes, then drain the whole lot, place back in the pot and set aside.
- Preheat the oven to 200°C (400°F), Gas Mark 6. Grease a 25cm (10in) square, ovenproof baking dish, approximately 5cm (2in) in depth.
- Add the milk to a saucepan over a medium–high heat and then whisk in the butter and flour. Continuously whisk until the mixture comes to a steady simmer and continue to cook until you have a thick sauce.
- At this point, it's time to add a bit of flavour, so add the wholegrain mustard, a pinch of nutmeg and three-quarters of the cheese, and season with sea salt and ground black pepper. Mix through until the cheese has melted. Pour the cheese sauce over the contents of the cooking pot and mix through until everything is combined.
- Pour the contents of the pot into the baking dish, sprinkle with the remaining cheese and pop in the oven to cook for 25 minutes or until the top has turned golden and the sauce is bubbling up the sides. Remove from the oven and allow to cool slightly before serving in big, deep bowls.