Start by placing your pot over medium heat and adding the butter and olive oil together. This combo gives you flavor from the butter and stability from the oil. Once melted, add the chopped onion and cook slowly for about 5–7 minutes, until soft and translucent. You’re not rushing this part—sweet, gentle onions are the backbone of the soup.

Add the garlic and cook for another 30 seconds, just until fragrant. The kitchen should already smell incredible.

Add all the sliced mushrooms to the pot. It will look like a lot, and that’s okay—they cook down significantly. Stir well, coating them in the butter and onions. Let them cook uncovered for 10–15 minutes, stirring occasionally, until they release their moisture and start to brown.

This step is everything. Browning the mushrooms deeply is what gives the soup its signature richness and savory depth.

Sprinkle the flour over the mushrooms and stir well, making sure there are no dry pockets. Cook for about one minute to eliminate the raw flour taste.

Slowly pour in the broth, stirring constantly. Bring the soup to a gentle simmer and let it cook for 10 minutes, allowing the flavors to meld and the soup to slightly thicken.

Using an immersion blender, blend the soup until smooth, or leave a bit of texture if you prefer. Stir in the milk, heavy cream, salt, pepper, and thyme. Simmer gently for another 5 minutes, then taste and adjust seasoning.

That’s it. Simple, steady, and incredibly rewarding.