Heat up the milk in a saucepan, this is important as it stops the sauce from splitting.
Melt the butter in a large pan on a low heat.
Whisk in the flour, one spoon at a time.
Slowly add the hot milk, whisking all the time.
Add the mustard, stock powder, dried herbs, nutmeg, nutritional yeast, salt & pepper vegan cheese if using. Whisk over a low heat until the sauce has thickened.
Add the vegetables to a pan of boiling water and cook until they are to your liking, I prefer my veggies al dente but I know some people like them really soft! Drain them and then put in a lasagne dish.
Pour the cheese sauce over them.
Sprinkle the breadcrumbs and rosemary all over the top then drizzle with the oil.
Place under a hot grill for a few minutes until the breadcrumbs have toasted.
For the breadcrumbs I just add some bread to my blender until it's broken down into small pieces. I used a sourdough for this but you could use any kind of bread you like.