This recipe uses olive oil instead of butter which reduces saturated fat by 70%, but still makes a flavorful and silky-smooth sauce. Use a mild-tasting olive oil - bolder oils that are good to finish dishes can be a little bitter in larger amounts.
Heat both olive oils in a small saucepan over low until warm, about 120°F.
Combine yolks, 3 tablespoons warm water, lemon juice, salt,white pepper and cayenne in a blender. Pulse until combined. Pour heated oil into a spouted measuring cup.
With blender running, slowly add oil in a thin, steady stream. If sauce is too thick, add up to 2 tablespoons warm water, 1 tablespoon at a time, and process until desired consistency is reached.
Serve warm over Eggs Benedict, asparagus, fish, chicken, or vegetables.