I have an order for a birthday cake for a client's husband's birthday and she came to me with the recipe she wants me to use.

The recipe will be assembled into 4 layers and iced very simply with Ganache and toasted nuts.

The recipe I've been asked to make results in a 4 layer 9" cake. The recipe says it serves 12 but it's SOOO rich, I know I can probably get at least 24 servings from it.

However I need cake for 60. Which is a 14" cake right?

I did some math. The volume of a 9" x3" cake is ~191 while the volume of a 14" x 3" cake is ~461. That means I need 2.5 times the amount of batter (if you round it off)

Would you just adjust the ingredients or would you bake the recipe twice each in two layers and get a slightly shorter cake.

FYI here's the recipe:
http://www.bonappetit.com/magazine/2008/09/chocolate_cake_with_fleur_de_sel_caramel_filling

I would just triple the recipe. I'm not an expert in the science of baking, so if it wouldn't work maybe someone else can chime in.

It says it makes a 9", 2-layer cake. It says "serves 12" because they are cutting it in pie-wedge pieces and not rectangle pieces like we use.

Ignore the number of servings. Go by pan size.

I find that these kind of recipes tend to short you on the batter. I've seen recipes that say you can get three 8" round cakes (2" tall) and I BARELY had enough batter for two 8" rounds.

With that in mind, if it were me, I'd assume this recipe is the equivalent of 1 cake mix, +/-. I use 3 cake mixes for a 14" round in my convection oven. (In my home oven, I use 2 cake mixes. Not sure why the diff, but thats how it worked out for me).

I took the long way around to say that it sounds like your 2.5 calculation will work out great. And as always, if it doesn't ..... well fire up the mixer and make one more small batch!