Soak the cashew nuts in water for 10 mins and grind to a smooth paste. Keep it aside.
In a nonstick pan, add 1/2 tsp butter and saute the peas, capsicum well for 5 minutes or till done. Remove and keep it aside.
In the same pan, add the cooking oil, add the whole cumin seeds. When it splutters, add the onions, along with sugar. Fry till the onions turn colour.
Then, add the ginger garlic paste, saute till the raw smell leaves. Once the onion ginger garlic paste is cooked, add the chili powder along with cashew nut paste and slit green chilies.
Mix everything well and cook in simmer for few mins. Then, add the tomato puree, cook well for 2 mins.
Then, add the fried peas and capsicum, combine everything together and cook. Finally, add salt and a cup of water. Bring to boil and then simmer for 5 mins.
Finally add the remaining butter, cream if you are adding. Cook till the gravy thickens.