The first recipe of "The Nero Wolfe Cook Book" by Rex Stout is for Eggs au beurre noir. For the black butter sauce he gives the following instructions:
"In a skillet melt [...] four tablespoons of butter over a medium heat. When white waxy particles have settled to the bottom, pour the clear liquid off into a bowl. Return the clarified butter to the pan and continue to cook until it has turned a deep golden brown..."
Now I have tried this recipe with unsalted butter, with salted butter, using a low heat, a medium heat, enough heat to create a fire hazard. I also tried different methods of clarification, all to no avail. The "deep golden brown" is only achievable, as far as I can tell, with unclarified butter. Indeed it appears to be the toasted butter solids that produce the golden brown.
I would have given up on this recipe altogether if it wasn't corroborated by other sources. It makes me wonder if, for example, American butter differs substantially from European butter. Does anyone know if black butter sauce can be made with clarified butter?