Place a glass bowl over a saucepan containing barely simmering water (or use a double boiler,) the water should not touch the bottom of the bowl.

Melt the butter

Add the egg yolks and lemon juice. Vigorously whisk until the mixture is thickened and doubled in volume. Be careful not to let the eggs get too hot or they will scramble.

Slowly drizzle in the melted butter and continue to whisk until all the butter is added. Don't hurry this step, the sauce will split if you do.

Remove from heat, whisk in salt and pepper. Cover and place in a warm spot until ready to use for the eggs benedict. I put it in a thermos bottle.