Preheat the oven to 180°C.
Peel and cut the squash & sweet potatoes into 3cm cubes. Scatter them into a roasting tin.
Peel, then cut the onions into wedges. Peel the garlic. Add these to the roasting tin. Scatter the thyme leaves on top, season with salt & pepper and drizzle with the oil. (You can add a couple of pinches of chilli flakes and 1 tsp smoked paprika too, if using normal vegetable stock later.)
Toss, then bake for about 25 minutes until the veggies are golden.
Transfer everything, including the cooking jus, to a pan and add the herbs. Using a hand-held blender, process it into a thick purée. You can tip this into a jar and refrigerate for later use. w
When you're ready to make the soup, add the stock pot and water, bring to the boil and simmer for a couple of minutes. Drain the beans, then add them to the soup and warm through.
Serve warm.