Béarnaise sauce
Some assume Béarnaise refers to the Béarn region, a former province now in the département of Pyrénées-Atlantiques, in southwestern Franceto refer to the region of Béarn However, the sauce has no tradition in the cooking of the area, and Larousse has the name honouring Henri IV of France, a native of Béarn, and for whom the restaurant where the sauce was first shown was named.  Henri IV was often known as le Grand Béarnais