There are 10 levels in this skill. The Gourmet cooking skill is similar to the cooking skill but you make facincer food this time. In order to make the food, your normal cooking skill needs to be level 5. Or you could read the gourmet cooking skill books but I believe you won't be able to make any of the food. Just like the normal cooking skill, the lot trait Homey gives your sim a +50% skill gain increase.
To start you need to get an over, fridge, and a counter or just buy the gourmet cooking skill books from a bookshelf.
I found this easy to get along with the normal cooking skill. I had my sim just join the chef career and work their way up to the top. You won't get any extra skill gain for this while watching tv, so the best way is to bake your way to the top.