Brown the mushrooms: Heat the olive oil and 1 tablespoon of butter in a large heavy‑bottomed pot over medium‑high heat. Add the sliced mushrooms in a single layer (you may need to do this in two batches) and cook without stirring for 3–4 minutes until the undersides turn a deep golden brown. Stir and continue cooking for another 2–3 minutes – you’ll hear a gentle sizzle and see the mushrooms release then reabsorb their juices, turning a glossy, caramelised colour. Transfer to a bowl and set aside.

Sweat the aromatics: Reduce the heat to medium and add the remaining 2 tablespoons of butter to the same pot. Once it foams, add the chopped onion and a generous pinch of salt. Cook, stirring occasionally, for 5–6 minutes until the onion is translucent and soft, but not coloured – it should smell sweet and mild.

Add garlic and thyme: Stir in the minced garlic and the leaves from 4 sprigs of fresh thyme (reserve one sprig for later). Cook for 1 minute until the garlic is fragrant – you’ll notice its sharp aroma soften and become nutty.

Make the roux: Sprinkle the flour over the onion mixture and stir constantly for 2 minutes. The paste will turn a pale straw colour and smell slightly toasted. This step thickens the soup without leaving a raw flour taste.

Add the stock: Slowly pour in the stock while whisking continuously to prevent lumps. Bring the mixture to a gentle simmer – you’ll see small bubbles breaking the surface – and cook for 5 minutes, stirring now and then, until the liquid thickens enough to coat the back of a spoon.

Return the mushrooms: Add the reserved browned mushrooms back to the pot along with the remaining sprig of thyme. Simmer gently for 10 minutes – the mushrooms will soften further and infuse the broth with their deep flavour. The aroma at this stage is wonderfully earthy and herbaceous.

Blend until smooth: Remove the thyme sprig and discard it. Use a stick blender (or carefully transfer to a countertop blender in batches) to purée the soup until silky smooth. You’re aiming for a velvety consistency – no chunks unless you prefer a little texture.

Finish with cream: Stir in the double cream over low heat. Warm through for 2–3 minutes – do not let it boil, or the cream may split. Taste and adjust salt and pepper. The soup should be rich, creamy, and fragrant with thyme.

Serve: Ladle into bowls and garnish with a few fresh thyme leaves and a drizzle of extra cream if you like. The colour will be a warm, pale brown – inviting and comforting.