Cut the squash into small chunks, toss with 1 tablespoon of the olive oil and spread out on the baking tray. Roast for 15 minutes or until soft.
Heat the remaining oil in a frying pan over a med/low heat and gently fry the onion until soft and translucent. Add the garlic and thyme and cook for a further minute.
When the squash is cooked, add it to a blender or food processor, along with the onions and milk. Whiz until smooth and creamy, taste and season if necessary. If the sauce seems too thick, add a little extra vegan milk to thin.
Cut the cauliflower florets into large pieces, then steam over a pan of simmering water until cooked.
Pour desired amount of the sauce over the cauliflower and serve with thyme leaves to garnish.
Save any leftover sauce for another meal in the fridge or allow it to cool and freeze. This is a lovely side dish for a roast dinner or served alongside a hot salad.