Prepare the base. Place the diced potatoes, chopped onion, minced garlic, butter, salt, pepper, and smoked paprika into the slow cooker insert. Pour the chicken stock over the top and give everything a good stir. The butter will sit in small yellow flecks across the surface, and the stock should just about cover the potatoes.

Slow cook until tender. Cover and cook on low for 6–8 hours or on high for 3–4 hours. You will know the potatoes are ready when you can easily pierce a cube with a fork and it offers no resistance. The liquid will look cloudy and slightly thickened, and the aroma of buttery garlic will fill your kitchen.

Blend to your desired texture. Using an immersion blender, blend the soup directly in the slow cooker until it is completely smooth and velvety. If you prefer a chunkier soup, blend only half and leave some potato pieces intact. The colour will shift from a pale, brothy beige to a rich, creamy off-white as the potatoes emulsify into the stock.

Add the dairy. Stir in the whole milk, double cream, sour cream, and half of the grated cheddar cheese. Continue stirring until the cheese has fully melted and the soup turns a uniform, pale golden colour. The texture should be thick enough to coat the back of a spoon but still pourable. Taste and adjust the salt and pepper if needed.

Warm through gently. Cover the slow cooker again and cook on low for a further 15–20 minutes. Do not let it boil at this stage, or the dairy may separate and the soup will develop a slightly grainy texture. You will see small bubbles breaking the surface, but no vigorous rolling boil.

Serve and load. Ladle the hot soup into bowls. Top each serving with the remaining grated cheese, a generous dollop of sour cream, and a scattering of sliced spring onions. The cheese will begin to melt immediately against the hot surface of the soup, creating those irresistible, stringy pockets of goodness.