This Northrend Cooking leveling guide will show you the fastest way how to level your Northrend Cooking skill up from 1 to 75 as inexpensively as possible.
Often the materials are based on a case that you will gain one skill point for each craft. This won't happen, so you will have to buy a few extra materials while you are leveling your Northrend Cooking.
Trainer Location
You can learn Northrend Cooking from Awilo Lon'gomba (Horde), or Katherine Lee (Alliance) in Dalaran (Northrend).
Leveling Cooking
1 - 25
The Cooking trainer will teach you a lot of recipes, most of them will turn green at 20 and gray at 40. (Sauteed Goby, Grilled Bonescale, Smoked Rockfin will turn grey at 5)
Get around 30-35 from any of these meats/fishes below. It doesn't have to be all from one. Then cook them using the recipes you learned from your cooking trainer.
[Worm Meat]
[Shoveltusk Flank]
[Worg Haunch]
[Rhino Meat]
[Chunk o' Mammoth]
[Glacial Salmon]
[Nettlefish]
[Fangtooth Herring]
[Musselback Sculpin]
If you did some questing in Sholazar Basin, it's worth going to the Dalaran Underbelly (sewers) and checking the Washed-Up Mage. If you completed the needed quests in Sholazar Basin, he will offer you the quest 
Fletcher's Lost and Found, which will teach you how to make 
[Kungaloosh]. After that, go to the Dalaran Fruit Vendor and you can just buy the materials from him, then make this recipe up to 25.
It's not worth doing the quest chain in Sholazar Basin just to unlock Kungaloosh because it takes more time than to farm the needed 30-35 meat for the other recipes. I only recommend this to people who already completed the quests.
25 - 75
The Northrend Cooking trainers won't teach you any more recipes, you have to buy the cooking recipes from Derek Odds (Alliance) or from Misensi (Horde) for 3 
[Epicurean's Award] at Dalaran.
[Epicurean's Award] is rewarded for completing the daily cooking quests. You will get a minimum of 3 [Epicurean's Award] a day, but some of the daily quests reward you with two, so you can actually get up to 5 a day if you are lucky.
You can get the daily quests from Katherine Lee (Alliance) or Awilo Lon'gomba (Horde) in Dalaran. And from Marogg (Horde) or Robby Flay (Alliance) in Orgrimmar and Stormwind.
I will list a bunch of recipes below and the required meat/fish to make them. Check the Auction House which meat/fish is the cheapest and buy that recipe. If you can't buy enough meat/fish to make a recipe around 60 times, then you have to wait another day so you can complete another two cooking dailies.
Make around 60 from any of these:
[Spiced Mammoth Treats] - [Chunk o' Mammoth]
[Tracker Snacks] - [Shoveltusk Flank]
[Blackened Worg Steak] - [Worg Haunch]
[Critter Bites] - 2 x 
[Chilled Meat]
[Hearty Rhino] - [Rhino Meat]
[Cuttlesteak] - 
[Moonglow Cuttlefish]
[Firecracker Salmon] - [Glacial Salmon]
[Imperial Manta Steak] - 
[Imperial Manta Ray]
[Poached Northern Sculpin] - [Musselback Sculpin]
[Blackened Dragonfin] - 
[Dragonfin Angelfish]
[Spicy Blue Nettlefish] - [Nettlefish]
[Spicy Fried Herring] - [Fangtooth Herring]
All of these recipes also require 1 
[Northern Spices]. You will get a few of these from the cooking daily quest, but only a few, so you should buy them from the Auction House, or wait a day to make more cooking daily quests then you can buy 10 [Northern Spices] for one [Epicurean's Award] at the vendor near your cooking trainer at Dalaran (Northrend).
I hope you liked this Northrend Cooking leveling guide, congratulations on reaching 75!