Slice the shallots in a fiber-breaking direction.
Add the shallots, garlic, butter and a pinch of salt to the pan and fry over low heat.

When the onions are soft, slice the mushrooms and add them to the pan.

When the mushrooms are also chunky, add the water and soup stock and bring to a boil over high heat.

Reduce the heat to low, remove the scum, cover with lid and simmer for 20 minutes.

Then remove from heat and blend in a blender until smooth. If using a hand blender, use a longer blender as it is less powerful - about 3-5 minutes.

When smooth, return to the pan and reduce to a simmer over medium heat.
When the volume has reduced by about 10%, add the cream and thyme.