I'm at a place in the game where an NPC would like some rotworm stew. I got the recipe from an NPC on Level 1 (although I no longer have the slip in my inventory, if that makes a difference). I have the ingredients and have placed them in a bowl, but I can't trade a container to this npc.

I assume I have to cook it so that it becomes 'stew' instead of a 'bowl with stuff in it', but I have no idea how to do that. I looked up some walkthroughs online, but there are were no details other than 'Give the NPC the stew'. I assume I'm missing something obvious, and I hope someone can give me a clue!

Edit: Thank you, Namur!