Try the blooming technique. When coloring buttercream I take a small amount, like 1/4 cup, and mix my color into it. Lots of color, way deeper than you want your finished color to be. Then melt the colored stuff in the microwave or in a small pan. Do not make it hot, just melted. The color will deepen intensely. A bit at a time, add the melted colored buttercream to your white buttercream until you get the color you want.
5/30/14 at 3:48pm