This is taken straight from allrecipes.com - I have made this recipe twice and it works like a charm!
3 egg yolks
1/4 tsp. Dijon mustard
1 T. lemon juice
1 dash hot pepper sauce (ex. Tabasco)
1/2 cup butter
1. In the container of a blender, combine egg yolks, mustard, lemon juice and hot pepper sauce. Cover and blend for about 5 seconds.
2. Place the butter in a glass measuring cup. Heat butter in the microwave for about 1 minute, or until completely melted and hot. Set the blender on high speed, and pour the butter into the egg yolk mixture in a thin stream. It should almost thicken immediately. Keep the sauce warm until serving by placing the blender container in a pan of hot tap water.
We serve this over poached eggs (I love my new pan) for eggs Benedict.
My kids love it! You may also serve it over steamed veggies.