We don't receive Gnaw's favour on some meals.

you only get favours from those on desert rounds.

1 hour ago, Zarklord said:

you only get favours from those on desert rounds.

We don't get them on deserts either.

If the meal isn't fresh you get a penalty on the value of the reward. Either rebuy fresh milk or salt the dish before sacrificing it.

We did't receive Gnaw's favour on
-Mashroom soup, when the craving is snack or veggy. 

-Cheese cake without plate, when the craving is cheese.

-Manicotty, when the craving is cheese.