Wipe off any dirty mushrooms (don't wash) and chop them.
In a heavy bottomed/cast iron pot melt 1 tbsp butter.
Add the olive oil, thyme and chopped onion, cook on medium-low until the onions are clear, then take off heat.
In a separate pan melt the remaining butter and add the chopped mushrooms, cook over medium until mushrooms are tender and have reduced in size.
Cover mushrooms with flour and stir to coat.
Add wine to the mushrooms and stir until combined, cook over low for 1 minute.
Transfer the wine/flour mixture to other pot containing the onions.
Add in the stock and stir to mix the wine/flour mixture throughout, and bring to a boil.
Reduce heat and simmer for 15 minutes.
Add the cooking cream and season with salt and pepper to taste.
(Optional) If you prefer a smoother soup, you can remove some of the soup (if you still want some chunkier pieces) and using an immersion blender, blend what remains in the pot. Then add back the chunky pieces.
Stir and heat the mixture over low (we do not want it to boil) and serve hot.