Prepare the ingredients:
Clean the mushrooms by gently wiping them with a damp cloth or paper towel to remove any dirt (avoid rinsing them with water, as mushrooms absorb moisture). Slice the mushrooms evenly. Finely chop the onion and garlic, and set them aside.

Sauté the mushrooms and aromatics:
In a large pot or Dutch oven, heat the butter and olive oil over medium heat. Add the chopped onions and sauté until soft and translucent, about 5 minutes. Add the minced garlic and cook for another 1 minute, until fragrant.

Cook the mushrooms:
Add the sliced mushrooms to the pot. Stir well to coat them in the butter and oil. Allow the mushrooms to cook, stirring occasionally, for about 8-10 minutes until they release their moisture and begin to brown. This helps intensify their flavor.

Deglaze the pot:
If using, add the dry white wine to the pot to deglaze, scraping up any bits stuck to the bottom of the pan. Let the wine cook off for about 2-3 minutes. If you’re not using wine, skip this step.

Add the broth and seasoning:
Pour in the vegetable broth, add the thyme and bay leaf, and stir to combine. Bring the soup to a gentle boil, then reduce the heat and simmer for 10-15 minutes. This allows the flavors to meld together.

Blend the soup (optional):
For a smoother soup, use an immersion blender directly in the pot to blend the soup until smooth. Alternatively, you can transfer the soup in batches to a stand blender. If you prefer a chunkier texture, you can blend only half of the soup or leave it as is.

Thicken the soup (optional):
If you prefer a thicker soup, whisk the flour into the heavy cream in a small bowl to create a slurry. Gradually stir this mixture into the soup, then continue to simmer for another 5-7 minutes until the soup has thickened. You can also skip this step for a lighter consistency.

Finish with cream:
Stir in the heavy cream (or coconut cream for a dairy-free version) and cook for an additional 2-3 minutes to heat through. Taste the soup and adjust the seasoning with salt and pepper.

Serve:
Remove the bay leaf and discard it. Ladle the soup into bowls and garnish with fresh parsley or thyme. Serve with warm, crusty bread or a side salad for a complete meal.