With the Burning Crusade upon us, Cooking has been expanded to a new cap of 375. Even more importantly, new buff foods have been added that not only help with the new level grind but are sure to become staples of the raider's repertoire. Luckily Blizzard has made it quite easy to level Cooking -- to a point.
Depending on your needs, there are a couple of ways to max out your Cooking skill. If you're in a hurry and just want to blaze through I think the easiest way is to collect 4-5 stacks of Whitescale Salmon. You can easily reach 350 skill just cranking these out. The recipe actually goes gray at 355, but the points are very slow once you hit 350 so it may not be worth it to you beyond that.
The way that I would recommend skilling up your Cooking is by adventuring. There are a good number of recipes that will see you easily through the first fifty skill points. In Hellfire Peninsula you can purchase the recipe for Ravager Dogs and do the quest chain for Buzzard Bites. You will kill enough buzzards and ravagers during your time in Hellfire to easily gain 20 skill points cooking up the dropped meat. Plus the Ravager Dog has a great +40 attack power buff and who can say 'No' to attack power?
More importantly, adventuring is the only way to gain access to some of the recipes you'll need later. You need to reach Neutral with Kurenai in order to purchase from Doba in Zangarmarsh and Nula in Nagrand (Uriku and Gambarinka for Horde players). If you don't quest in either of those zones you won't have the proper faction to purchase their recipes. In my opinion it's more fun to level Cooking this way so you can use the food you're creating while you quest in each new zone.
Once you are 320-325 Cooking skill (and Neutral Kurenai faction, you should try to visit Nagrand and purchase all the cooking recipes from Nula/Uriku. You'll need to kill some of the critters in Nagrand for the necessary ingredients, or if you've already completed Nagrand you were hopefully smart enough to save drop components. Most people will probably have a ton of Talbuk Venison and Clefthoof meat from the "Mastery" quests to reach 350 Cooking skill. There are also several types of fish you can cook at this point if you have Fishing, such as the Icefin Bluefish, Figluster's Mudfish and the Golden Darter. You healers out there will love the Golden Darter for the healing buff you gain by eating Golden Fish Sticks.
Most of the Nagrand recipes for 325 skill will see you safely to 360-365, which is good since there are no new recipes between 325 and 350. When you reach 350 in Cooking there is only one new recipe available, the Spicy Crawdad. This can be purchased from Innkeeper Biribi at the Allerian Stronghold (Rungor at Stonebreaker Hold for Horde) and it's the only recipe that will allow you to max out Cooking for Alliance players. I've been told that there are couple of quest recipes for Horde players in Blade's Edge Mountains that will allow them to reach 375 in Cooking, but I can't personally confirm this.
This is also the point where Blizzard really sticks it to us. The Furious Crawdads required to make this recipe can only be fished out of three lakes in Terokkar Forest. Those lakes can only be accessed with a flying mount. And the fish will only be caught from special spawned pools of "highland mixed schools" at the lakes in question. So for the most part you will not be maxing out your Cooking until you are level 70 (68 for druids) and have your flying mount. You also need a base Fishing skill of 350 to fish these lakes. Even at 350 your fish will get away 75-90% of the time, so a higher fishing skill is recommended. I did it at 350 and 9 out of 10 casts produced an 'escapee' instead of a fish, which is very frustrating. At that point I knew how those crawdads had gotten their name because I was furious at those little boogers for eluding me!
There is a very detailed fishing guide written by El of Ravenholdt called Catching Furious Crawdad and Mr. Pinchy which I highly recommend reviewing before you head out. He has a very nice map which shows where to find the lakes and how to find the spawned fishing pools.
If you don't have 350+ Fishing skill on at least one level 70 toon it's unlikely that you'll be able to max out your Cooking. You can certainly try camping the Auction and hope some other player decides to sell their crawdads, but given the difficulty involved in catching them I would be surprised if many players were willing to give them up. I took a peek at the AH on my server and the crabbies were going for 3+ gold each. Ouch!!
For those of you who make it to 375... Congratulations on a job well done!