Leto, cooking same dish 10 times increase base quality of meal by one degree (from normal to nice, from nice to very nice). Top quality is perfect, but sometimes Sims get +75 amazing meal moodlet instead of +50 which is usual for perfect food (and it is not their favorite food that makes a difference).
If you drink nectar after meal, you'll get +5 on meal moodlet (and get +80 divine meal), with overemotional I got +97 or +98, can't really remember, but haven't been able to go over 100.