French Buttercream
This buttercream recipe contains egg yolks and is adapted from "Professional Baking." While an industry recipe, scales down well for home use.

2 lb. sugar
8 oz. water
12 oz. egg yolks
2 1/2 lbs. butter
1/2 oz. vanilla

Bring the sugar and water to a boil, and continue to boil until 115°C. While the sugar is boiling, whip the yolks in a stand up mixer until they are thick and very light. When the sugar comes to temperature, remove from heat and slowly add in a stream to the whipping yolks, on a medium-low speed. Continue to whip until yolks are completely cooled. Mixture will be light and thick. While machine is running, add in the butter in chunks, but add it only as fast as can be absorbed into the mixture. Last, add in the vanilla.