Boil the cauliflower, broccoli, carrots till cooked(about 10-15 mns)
Gently fry the garlic,leeks,spinach and pepper till softened
Make the cheese sauce
Melt the butter in a small pan
Add the flour and stir till its combined
Add the milk and stir till its smooth.
Add the cheese,herbs and mustard
Continue stirring till sauce thickens
Combine all vegetables in an ovenproof dish
Pour over cheese sauce
Top with grated cheese
Cover with breadcrumbs
Bake in oven for 30-40mns at 200'