I'm blown away by how good this was, much better than most of the restos I've been to, and so easy to make too! My first attempt and I am so excitedly in love with it.

you'd need:

1. mushrooms (I used 2 boxes, one white and one chestnut) - when peeled they filled a medium pot
2. red onions / garlic - this is to taste, so up to you if you want to leave this out. I threw them in since they were going to expire.
3. 500ml of water + chicken stock cube (or just 500ml of whatever stock)
4. 1 cup (300ml) of heavy cream (I used jersey thick cream).

so basically:
1. wash mushrooms and break them up into smaller pieces. fry in coconut oil (or butter) with onions and garlic until they look cooked. there will be water coming out which is fine. my pot was too small so I used a pan as well.

2. in a pot, with the cooked mushrooms / onions / garlic / mushroom juices, add in your water / chicken stock. bring to boil. after 3 mins or so, bring to a simmer or 10-15 mins. (optional adding of chili / flakes)

3. throw into blender and blend until you like the consistency. you can also save up some mushrooms to mix into the blended soup later, if you like chunks of mushroom in your soup.

4. pour blended mix back into pot, on a low heat, whisk in the heavy cream

5. serve once whisked! added black pepper and garlic toppings to mine.

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it makes quite a decent sized pot of soup and incredibly yummy. if you want it thicker / thinner, adjust the cream amount. I can't believe I didn't make this sooner!