Sauté the mushrooms: In a large pot or Dutch oven, heat 2 tbsp olive oil and 2 tbsp butter over medium-high heat. Add the chopped 3 lbs of mixed mushrooms and cook for 10-15 minutes, stirring occasionally, until mushrooms release their juices and start to brown. Season with salt and pepper as they cook.

Add aromatics: Add the onion and cook for another 5-6 minutes until softened. Stir in the roasted garlic, mashing it with a spoon to incorporate.

Blend for a smooth base: Transfer the mixture to a blender (in batches if necessary) and blend until smooth. Alternatively, use an immersion blender directly in the pot until mostly smooth but still textured.

Return to pot and add stock: Pour the blended mixture back into the pot. Add the chicken stock and bring to a gentle simmer. Let it cook for about 10 minutes, allowing the flavors to meld.

Add sliced mushrooms for texture: In a separate pan, heat the remaining 1 tbsp of butter. Sauté the 1 lb of sliced mushrooms until they’re golden and tender, about 6-8 minutes. Add these to the soup for texture.

Finish with creams: Reduce the heat to low, then stir in the half & half and heavy whipping cream. Heat gently, stirring occasionally, until warmed through, about 5-10 minutes. Do not let it boil to prevent curdling.

Adjust seasoning and serve: Taste and adjust with salt and pepper as needed. Garnish with fresh thyme or parsley if desired.