Basically, I roasted in the oven the courgettes, cherry tomatoes, onion, garlic and sweet potato. (Toss 'em all in a li'l olive oil and then roast for about 30 to 40 minutes. I like 'em roasted quite black, you might not!
Then I peeled, seeded and chopped the squash, chopped the carrots, peeled and chopped the apple and threw everything in the slow cooker: all veg, the coconut milk and 2 cups of water. You could also use chicken stock, but to be honest, there are so many flavours here not sure you need to! Up to you.
Forget about it in the slow cooker on low for about 4-6 hours. Then blitz with a hand blender. Add more water if it's too thick. (I had to.)
Enjoy with parmesan 'croutons' like I did. Or however you enjoy soup.
To be honest, this is one of those recipes that you can look at, then look in your fridge, then adapt. Don't have courgette? Don't worry. Add peppers. Need to use up some roasted parsnips? Throw them in.