Peel and slice the onions and garlic.
Melt most of the butter in a deep pan and sauté onions, garlic, and grated ginger.
Crush the cardamom seeds and add them to the pan with all remaining dried spices and bay leaves.
Add the mushroom pieces and remaining butter to the pan and cook for two minutes.
Cover the pan with a lid and cook until mushrooms soften.
Add 200ml of water, cover, and simmer for 15 minutes.
Wilt the spinach in a separate pan then cool under water and squeeze dry.
Stir the spinach, hazelnuts, raisins, yoghurt, and crème fraîche into the korma.
Gently warm the mixture through and serve.