To make white gravy paste, soak diced onion, ginger, garlic, cashew, and green cardamom in hot water for 15 minutes. Later, blend them to a smooth paste using hot water.
Heat oil in a kadhai or casserole. Once hot, add cumin seeds and bay leaf. Fry for 20 seconds
Add the white gravy paste prepared earlier. Fry the paste for 2 - 3 minutes over low heat or until the oil separates from the masala Keep stirring while frying the masala.
Add diced button mushrooms, green peas, salt, and saute for a minute. Add 1 Cup of water, and stir to combine.
Cover and cook the gravy over low heat till the mushroom and peas are fully cooked. This usually takes less than 10 minutes.
Open the lid, add garam masala, cumin powder, black pepper powder, cream (malai), and fresh fenugreek leaves. Stir to combine.
Simmer the methi matar malai over low heat for the fenugreek leaves to soften and cook. Do not cook for more than 5 - 6 minutes.
Serve mushroom methi matar malai with naan or jeera rice.