Slice mushrooms, chop onion, and mince garlic. Warm the broth so it’s ready.

Heat a large pot over medium-high heat. Add butter and let it foam.

Add mushrooms in a single layer if possible. Let them brown without stirring for 2–3 minutes, then stir and continue until nicely caramelized (about 8–10 minutes total). Don’t crowd the pan.

Add chopped onion. Cook until softened and translucent, about 5 minutes.

Stir in garlic, marjoram, and thyme. Cook for 30–60 seconds until fragrant.

Pour in chicken broth. Bring to a simmer and cook for 10–12 minutes to meld flavors.

For a smooth soup: remove 1–2 cups of solids and purée in a blender or use an immersion blender directly in the pot.

Reduce heat to low. Stir in heavy cream and warm through — do not boil once cream is added.

Season with salt and freshly ground black pepper to taste. Serve immediately.