So I worked out what brings up your cooking level the quickest per meal... and the answer is, the level of the buffs it bestows. Something with several level 10 buffs will give far more than the early game meals. A fairly easy meal is the mother child rice bowl:
"To unlock the Mother and Child Rice Bowl recipe, you need to see a woman at Overlook in Lestallum eating." - Edit - the overlook is the part at the front of Lestallum, she'll be by the picnic tables.
INGREDIENTS
Chickatrice Leg
Birdbeast Egg
Saxham Rice
BONUSES
HP Boost (Level 20): Increases maximum HP by 1,000.
EXP Boost (Level 3): Increases experience points earned by 30%.
Perception Boost (Level 5): Increases perception by 50%."
You can buy the Saxham rice and the Chickatrice legs and Birdbeast Eggs between Wiz's outpost and Lestallum. Bonus to this is you can also get +1 AP for it being a favourite food. Alternatively, my suggestion would be to save this till late game and mass buy some ingredients from Cape Caem and Lestallum. I found the meals that required Fine Cleigne Wheat were a good call.
Whatever method you choose the quickest way to cook is mass camp at one camp site using high buff bestowing meals. If you wish to couple this with AP Farming and Gladio's Survival skill, you can max out the camping AP earners and then run between the 3 camps around hammerhead. Each different camp you choose gives you bonus AP (as long as its different from the last).
P.S. For people who own the DLC which gives you the Cheese Pizza recipe, DON'T cook it as it will not increase your cooking level. (Gourmet DLC, currently free at least in EU)