“Pudding” here is not just a creamy dessert, it’s just dessert in general. It’s like going to the States (especially the South), asking for a “Coke,” and getting the response back “What kind’a Coke do ya want? We gots Pepsi, 7-Up, Dr. Pepper…”
Notable Example:
“how can you have any pudding if you don’t eat your meat?â€
-Pink Floyd.