Freeing Evil Dave

Official quest description: Evil Dave needs some kind of spicy stew. You will need Evil Dave's help for this one. He lives in his mother's basement in Edgeville...
Release date: 15 March 2006
Start: Inspect Evil Dave.
Difficulty: *****
Length: Medium-Long
Members only: Yes
Requirements:
Level 25 cooking
Completed Gertrude's Cat
Completed Shadow of the Storm
Items needed:
wily cat, cat, kitten, or lazy cat (overgrown cats don't work as they do not hunt rats, also a kitten is not recommended because the chance of them catching a rat is a low 5% compared to 80% for a normal cat)
At least 9 bowls of stew (bring more to be on the safe side, maximum you can need is 12).
Monsters to kill: None
Spoiler warning: Plot and/or ending details follow.
[edit] Walkthrough

Evil Dave's Dungeon.

Evil DaveGo to Edgeville. The house west of the bank is Evil Dave's mother's house. Talk to Doris and ask her either question. Then climb down the trapdoor. You will see that Evil Dave has gotten into summoning demons as well. However, they are Hellrats, the weakest form of demon ever. Talk to him and ask him what he ate at the feast. He'll ask you why, and you tell him that it is because the magic requires him to do so (the 4th option). He'll tell you that it was a perfectly spicy evil stew, like the ones his mother makes. Talk to Doris (Dave's mother) again. She will tell you that the demons stole all of the spices. With your cat, catch Hellrats (after 7, it will turn into a hellcat or hellkitten. These serve the same purpose as a regular cat. To change them back, talk to Doris or give it a bucket of milk). Then add the spices to your stew. Dave will eat the stew, then tell you how many spices are correct.
[edit] Strategy
There are two ways to do this part:
First, you can go to Questhelp and unlock the spoiler, giving you exactly how many spices you need.
Second, you can figure it out yourself:
This game is sort of like a game of mastermind. The best strategy is to have lots of stew in your inventory (9 is the maximum you will need barring mistakes.) Have your cat catch hellrats to get spices. Spices can be red, yellow, brown, or orange, and may have from 1 to 4 doses per shaker caught. The perfect stew will have between 1 and 3 doses of each of the four colours.

Your cat has become a hellcat!
Figure out each colour separately. Using red as an example: Add one dose of red spice to your stew, then ask Dave to eat it. If he says that one spice is right, stop and move on to the next colour. You know that you need 1 dose of red spice. If he says that no spices are right, add 2 doses of red spice to your next stew. If 2 doses are correct, stop and move on to the next colour. If no spices are right, the answer must be 3 doses. Do not try out 3 spices, as using this method it must be three. Move on to another colour, using a single dose of that colour, and repeat this process through all four colours.
If you run out of stew, use the canoes to travel to Lumbridge to make more or you can go East for a small distance to the Grand Exchange and alternatively buy stew from players, however, you will not use more than two stews per colour using this strategy, thus the maximum you will have to use is eight stews (plus the last one, which will be perfect.)
After you figure how much of each colour to put in the stew, use that much of each colour on one stew. This will be the perfect stew. Ask Dave to taste it (don't worry, if it's right, he won't eat the whole thing). Take the perfect stew to his frozen alter ego to protect him