Maza aa Gaya is a common Hindi expression meaning I really enjoyed this. It is the natural cultural response in India when someone appreciates food prepared by their mother.
This is a light, subjective/cultural question rather than a factual one — 'Maza aa gaya' (Hindi for 'that was fun/enjoyable') is the marked colloquial reaction chosen as the expected response, reflecting a common informal expression of delight over a home-cooked favorite dish.