Place egg yolks and 1/3 of the butter in top of double boiler. Cook over hot, not boiling, water till butter melts, stirring rapidly. Add 1/3 more of the butter and continue stirring. As mixture thickens and butter melts, add remaining butter, stirring constantly. (Water in bottom of double boiler should not touch top pan.)
When butter is melted, remove pan from hot water; stir rapidly 2 minutes longer. Stir in lemon juice a teaspoon at a time; season with dash salt and dash white pepper. Heat again over hot water, stirring constantly till thickened, 2 to 3 minutes. Remove from heat at once. If sauce curdles, immediately beat in 1 or 2 tablespoons boiling water. Makes 1 cup.
NOTE: If your sauce breaks (separates), like mine did this morning, immediately pour into a blender and turn on blend setting. Then continue adding lemon juice. As you can see my sauce turned out perfect!