Preheat the oven to 180°C. Grease an ovenproof dish with nonstick spray.
1 Heat the oil in a pan and fry the onion until fragrant. Add the mushrooms and stir-fry until soft, then add the bay leaves, cumin and masala and stir-fry until fragrant.
2 Stir the butter in and sprinkle the flour over. Mix well, then add the yoghurt. Heat while stirring continuously. Lastly, mix in the mayonnaise and lemon juice.