Try the variations too!
Yield: 2/3 cup
In blender, mix all ingredients except butter. Slowly pour in butter while mixing on low speed. Refrigerate if not using immediately. Variations: Blender Bearnaise Sauce: (For broiled meat and fish.) To sauce in blender, mix in 1 tablespoon minced onion, 1 teaspoon tarragon leaves, 1/2 teaspoon chervil leaves and 2 tablespoons white wine or, if desired, 1 tablespoon white wine vinegar. Blender Mousseline Sauce: (For fish, eggs, artichokes, broccoli, cauliflower, and spinach.) Cool sauce to room temperature. Just before serving, beat 1/4 cup chilled whipping cream in chilled bowl until stiff; fold into sauce. About 1 1/4 cups.
Source: Betty Crocker Cookbook
Please note that some ingredients and brands may not be available in every store.