Sauté the aromatics: Heat the olive oil in a large, sturdy pot over medium heat. Add the onion and a pinch of salt; sauté for 5–7 minutes until translucent and lightly golden at the edges. The aroma should be warm and inviting.

Brown the mushrooms: Add the mushrooms in an even layer. Let them cook undisturbed for 4–5 minutes to develop color, then stir and continue cooking for 6–8 minutes until their juices release and evaporate. The mushrooms should look richly browned.

Add the aromatics: Stir in the garlic and thyme; cook for 30 seconds until fragrant. Avoid browning the garlic to keep its flavor fresh and bright.

Build the base: Sprinkle in the flour and whisk for 1–2 minutes to toast it slightly. This step helps the soup thicken smoothly.

Simmer: Slowly whisk in the vegetable broth, scraping up any browned bits from the bottom of the pot. Add the potato cubes if using. Bring to a gentle simmer and cook for 15–20 minutes, or until the potato is tender and the flavors meld together.

Add creaminess: Stir in the cashew cream (or plant-based milk) and heat through for 2–3 minutes, until the soup looks creamy and cohesive. For a smoother texture, blend about half of the soup with an immersion blender, leaving some chunks for depth.

Finish and serve: Taste and season with salt and pepper. If the soup feels too thin, simmer a few extra minutes; if too thick, add a splash of broth or water. Serve hot, garnished with fresh parsley or extra thyme sprigs.