Any recipes with a divided roux?

Are there any individual recipes or cuisines which make use of a divided roux? By "divided roux" I mean cooking a portion of roux to a certain level of color, removing half or so of the batch from the heat, and then continuing to cook the remainder of the roux to a darker color. I ask because there is a tradeoff between flavor and thickening power when it comes to roux: lighter rouxs (white, blonde) are better thickeners, but lack much flavor. Darker rouxs (brown, chocolate) lack much thickening power, but are more flavorful. Are there any classical recipes which attempt to capture the best of both worlds? Or do recipes with darker rouxs simply tend to call for other thickening agents (assuming such an agent is even needed in the dish), such as file powder? submitted by /u/Icarus367