Fold the chopped spinach into the pot and stir until it begins to wilt. Add the diced potato and mix everything so the heat reaches each piece evenly. The potato cooks alongside the greens and gives the soup its creamy body without relying on heavy ingredients.

Pour in the vegetable stock and sprinkle in the salt. Bring the pot to a mild boil, then shift to a gentle simmer. Let the potato soften completely; this ensures the final blend turns silky and consistent. While simmering, the spinach keeps its fresh green flavour instead of turning dull.

Turn off the heat and allow the mixture to cool slightly to avoid steam pressure in the blender. Blend until you get a smooth, uniform puree. If the mixture seems dense, loosen it with a splash of warm stock. A second quick blend helps achieve a velvety finish.

Pour the blended soup back into the pot. Stir in the milk, nutmeg, and black pepper. Keep the flame low so the soup heats gently without boiling. This prevents the milk from splitting and keeps the texture creamy and balanced.

Switch off the flame and stir in the lemon juice. This small amount brightens the soup and lifts the earthy flavours of the greens. Check the seasoning once more and adjust the salt if needed.