Check out thottbot or other such resources if you need specific drop rates/mobs or zones for any given recipe/item.

Most of the ingredients to level your cooking, even to the new 450 cap, can be bought off the auction house. Grab your ingredients and camp the trainer to level your skill. You will have to visit Gadgetzan to do the Artisan Cooking Quest, though. At 300 you will need to buy the Master Cookbook in Hellfire Peninsula (or off the Auction House.)

Once on Northrend talk to a cooking trainer, in any of the starting towns, for get your Grandmaster Cooking skills. Items highlighted in bold are also in the Tauren Chef Cookbook, allowing you to create these foods in the real world.

225 – Artisan Cooking Quest
Head over to gadgetzan for this quest, you’ll need to speak to Dirge Quickcleave to pick it up first, the objective being Clamlette Surprise.

To finish it 12 Giant Eggs, 10 Zesty Clam meat, and 20 Alterac Swiss is required.  The Alterac Swiss is the easiest to get as it’s buyable off a vendor named Ben Trias in the trade district of Stormwind City, Horde can buy it off the Thunderbluff inkeeper.

The second and third ingredients are gathered by killing Owlbeasts in the Hinterlands and Turtles in Tanaris, Eggs and Clam Meat respectively.  Once you’re done turn it all in and get ready for the ride from 225-375.

Alliance Cooking Guide
1 - 75

1 - 40: Spice Bread (1 x Simple Flour, 1 x Mild Spices) x 40
40 - 75: Smoked Bear Meat (1x Bear Meat) x 50
75 – 175

75 - 85: Crab Cake (1 x Crawler Meat) x 10
85 - 100: Cooked Crab Claw (1 x Crab Claw, 1 x Mild Spice) x 20
100 - 130: Seasoned Wolf Kabob (2 x Lean Wolf Flank, 1 x Stormwind Seasoning Herbs) x 30
130 - 175: Curiously Tasty Omelet (1x Raptor Egg, 1 x Hot Spice) x 50
175 - 225

175 - 200: Roast Raptor (1 x Raptor Meat, 1 x Hot Spices) x 30
200 - 225: Spider Sausage (2 x White Spider Meat) x 30
225 - 325

225 - 285: Monster Omelet (1 x Giant Egg, 2 x Soothing Spices) x 80
285 – 300: Smoked Desert Dumplings (1 x Sandworm Meat, 1 x Soothing Spices) x 20
300 – 325: Ravager Dog (1 x Ravager Flesh)
Note: You’ll need to buy the master cooking book off of Father Malgor Devidicus located within Honor Hold/Hellfire Penninsula before you can go past 300 cooking skill.
350 – 375

325 – 350: Roasted Clefthoof (1 x Clefthoof Meat) x 35-40
350 – 375: Spicy Crawdad (1 x Furious Crawdad) x 30-40
Horde Cooking Guide
1 – 125

1 - 40: Spice Bread (1 x Simple Flour, 1 x Mild Spices) x 50
40 - 75: Smoked Bear Meat (1x Bear Meat) x 60
90 - 125: Dig Rat Stew (1 x Dig Rat) x 40
125 – 225

125 – 175: Hot Lion Chops (1 x Lion Meat, 1 x Hot Spices) x 60
175 – 200: Roast Raptor (1 x Raptor flesh, 1 x Hot Spices) x 30
200 - 225: Spider Sausage (2 x White Spider Meat) x 30
225 - 325

225 - 285: Monster Omelet (1 x Giant Egg, 2 x Soothing Spices) x 80
285 – 300: Smoked Desert Dumplings (1 x Sandworm Meat, 1 x Soothing Spices) x 20
300 – 325: Ravager Dog (1 x Ravager Flesh)
Note: You’ll need to buy the master cooking book off of Cookie One-Eye located within Thrallmar/Hellfire Penninsula before you can go past 300 cooking skill.
350 – 375

325 – 350: Roasted Clefthoof (1 x Clefthoof Meat) x 35-40
350 – 375: Spicy Crawdad (1 x Furious Crawdad) x 30-40
375-450

Talk to the trainer in Northrend for Grandmaster Cooking, then harvest the appropriate parts from the animals in the area or off the Auction House.
Professions Guide
Penn's Professions Guide details all the secrets to leveling any WoW profession as quickly, efficiently, and cheaply as possible. From Cooking to Inscription to Enchanting the most effective way to max out your skill is with Penn's Guide. Check it out, here.