Pop butter in the pan with the leeks and onion & soften until slightly golden.
Add the Garlic, veggies, thyme and salt and sauté for a minute or two. Then top with the chicken / veggie stock.
Cook for 10 minutes, then turn off the heat and blitz with your stick mixer, adding the cream / coconut milk at this point if you’re adding it!
Taste and season with salt and pepper as you like!