Loaded with butter, Hollandaise isn't the healthiest sauce, but a little bit goes a long way. Since I believe in moderation rather than deprivation, I do indulge in some Hollandaise a couple of times per year. It's good with eggs as well as a variety of vegetables - from asparagus to green beans to brussels sprouts.
If you don't have a double boiler, you can improvise. Just place a heat-proof bowl (such as Pyrex) over a saucepan containing the boiling water, as shown in the photo below. The bottom of the bowl should not touch the water. This works just as well as a fancy double boiler.
2 egg yolks, preferably pasteurized
2 tablespoons freshly squeezed lemon juice
1/2 cup (1 stick) cold salted butter, cut into 8 equal pieces
Pinch of cayenne pepper
Pour 2 inches of water into the bottom part of a double boiler and bring to a simmer over medium-high to high heat. Once it reaches the boiling point, reduce heat to low, and keep it at a simmer.
In the top part of the double boiler, combine the egg yolks, lemon juice, and 2 pieces of the butter. Place over the simmering water and whisk until the butter is melted. Whisk in the remaining butter, one piece at a time, melting each piece before adding more.
When all the butter has been melted, stir in the cayenne.
If the sauce gets too thick, whisk in a little bit of water, 1 teaspoon at a time, to thin it to the desired consistency.
-- 4 servings (approx. 2/3 cup of sauce total)