Classic vegetarian comfort food. Can be used as a main meal or as a side dish.
Put the oven on to preheat at 200 degrees. Cut the cauliflower and broccoli into florets. Put these in a large pan and add water; simmer until tender - around 10 minutes.
Put the flora (or other low fat spread) into a medium saucepan on a low heat and allow to melt. Add the flour and stir to combine. Cook, stirring, for a minute or so.
Add the milk gradually, stirring all the time with a whisk to break up the flour mixture and blend the milk in. Add more milk each time the sauce re-thickens.
Do this until you have a nice thick sauce consistency. If you feel it's not getting thick enough, mix a bit more flour with some milk and slowly pour in, stirring all the time. Do this a little at a time to avoid over-thickening the sauce. Lumpy sauce can be rescued by passing it through a sieve.
When the sauce is ready, add salt and pepper and grate around 2/3 of the cheese into the pan. Then stir in the mustard.
Drain the cauliflower and broccoli and tip into a baking dish. Pour the sauce over the vegetables, trying to coat all the florets.
Sprinkle the panko breadcrumbs on top, and grate the rest of the cheese over it.
Bake in the oven on a high shelf until golden and a bit crispy around the edges. Serve in warm bowls. Some crusty bread goes well alongside.