I "think" each of us would reccomend a slightly different recipe.......but we'd all reccomend a pastry cream type base. If you have access to any professional pastry books they'll give you exact fomulas.
Personally I like to add my flavors into my base while preparing it. Depending upon what flavors your wanting many can be successfully added ala minute too.
I personally like to shop at www.chipsbooks.com
and would suggest an all around professional pastry book by Glissen or Frieberg. Not all books contain recipes for souffles.
P.S. If your not a pastry chef but your working in a professional setting with a convection oven.........don't forget when baking we don't use the temp. on the dial. We dial down about 25 to 50 degrees to compensate for the circulation air (even when baking a full ovens worth of product). You need to practice this before choosing your temp to bake your souffles. Because if you set your dial on 425 as is, and put a souffle in your convection, you'll get a burned top and a raw center.