Prepare your potatoes: Peel the potatoes and cut them into even 2cm cubes. I cannot stress this enough — even cubes mean even cooking. Rinse them under cold water until the water runs clear to remove excess starch. You'll see the water turn milky at first; keep rinsing until it's clear. This single step prevents your soup from turning stodgy and gluey. Drain well and set aside.

Sweat the aromatics: Place your large stockpot or Dutch oven over a medium heat and add the olive oil and butter. Once the butter has melted and is gently foaming — you'll hear a soft sizzle — add the diced onion and celery. Cook for 8–10 minutes, stirring occasionally, until the onions are translucent and softened but not coloured. You're looking for a pale golden appearance and a sweet, fragrant smell that fills the kitchen. Add the minced garlic and cook for one more minute until it releases its aroma — about 30 seconds is usually enough, as garlic burns quickly.

Build the base: Add the drained potato cubes to the pot and stir everything together for 2 minutes. The potatoes should look glossy and slightly coated in the buttery mixture. Pour in the stock, then add the bay leaves and dried thyme. Bring the mixture to a gentle boil — you'll see bubbles lazily breaking the surface — then immediately reduce the heat to low, cover the pot, and let it simmer for 20–25 minutes. The potatoes are done when you can easily pierce a cube with a fork and it offers no resistance. The smell at this stage is deeply savoury and comforting.

Blend to velvet: Remove the bay leaves and discard them. Using an immersion blender directly in the pot, blend the soup until it's completely smooth and velvety. If you're using a countertop blender, work in batches and never fill the jug more than halfway — hot liquid expands and can be dangerous. The texture should look like thick double cream, glossy and uniform. You'll see the soup transform from a chunky, rustic mixture into something that looks almost satin-like.

Finish with cream and seasoning: With the heat on the lowest setting, stir in the double cream. This is where the soup becomes truly luxurious. Taste and season with salt and white pepper. Be generous with the salt — potatoes need it to shine. The final soup should be rich, smooth, and coat the back of a spoon thickly but still flow easily. If it's too thick for your liking, add a splash of warm stock or milk to loosen it.

Rest and reheat gently: This is a step many people skip, but it's vital. Remove the pot from the heat and let the soup sit for 5 minutes. This allows the flavours to marry and the texture to settle. When you return it to a low heat to serve, stir gently. You'll notice the soup looks even silkier after this short rest — the starch molecules relax and the cream integrates fully.