Thinly slice the leeks into rounds then wash to remove any dirt. Drain well
Peel and remove the seeds from the squash and cut into bite sized chunks
Peel the sweet potato and cut into bite sized chunks
Break the broccoli into florets
Remove the core and seeds from the pepper and cut into largeish pieces
Halve or quarter the mushrooms if they're very large
Put the squash and sweet potato into a large frying pan or large saucepan that has a lid and add a drizzle of olive oil
Saute over a medium heat, stirring occasionally for 5 minutes. Add 1/2 cup (120ml ) water, put the lid on and bubble for a further 5 minutes
Remove the lid and allow the water to evaporate for a further 5 minutes
Add the leeks and peppers and saute for another 5 minutes, stirring frequently
Add the broccoli and mushrooms and 1 cup (240ml) water and put the lid on for a last 5 minutes.
Turn off the heat and remove the lid then wilt in the spinach - you might need to do this in a couple of batches - just stir it into the other veg until it shrinks then set the saucepan aside while you make the sauce
If you're planning on eating this after you've baked it preheat your oven to 180 Fan / 200 C / 400 F / Gas 6
In a medium saucepan put the 2 tblsp olive oil and the crushed garlic. Gently heat until sizzling then stir in the wholemeal flour to form a thick paste (also known as a roux)
Add the milk a little at a time, stirring well between each addition until you've used all the milk and you have a smooth creamy sauce. I start the roux with a wooden spoon then as I add more milk and it starts to loosen up I swap the spoon for a whisk
Add the vegan cheese, mustard, dried rosemary and plenty of salt and pepper and whisk to melt the cheese
Add the sauce to the veggies (or vice versa depending in which is the bigger pot!) and stir together until well mixed
At this point you can chill and refrigerate for use at another time or day otherwise pop into the oven for 20-30 minutes until piping hot in the centre
You can also reheat any leftovers - simply bake again until piping hot
Recipe by The Cook & Him at https://thecookandhim.com/recipes/vegan-cheesy-vegetable-bake/