In a very large saucepan, cook the
cauliflower in boiling salted water for
5 mins. Then add the broccoli and cook
for 3 mins more. Drain well and transfer
to a large ovenproof dish.
To make the cheese sauce, melt the
butter in a small pan. When foaming, add
flour and mustard powder, and cook for
1 min, stirring constantly. Take off the
heat and add the milk, a little at a time,
stirring constantly to get rid of any lumps.
Once half the milk has been added,
return to the heat and add the remaining
milk. Keep stirring and bring to the boil,
then turn down to a simmer and cook for
2 mins, until thickened and smooth. Add
most of the cheese and some seasoning
then take off the heat and add the chives.
Pour the sauce over the vegetables
and sprinkle with the remaining cheese.
This can be done the day before and kept
covered in the fridge. Cook in the oven
with the pork for 35-40 mins until bubbling,
allowing an extra 5-10 mins cooking time
if from the fridge. Serve with the pork.