Add the egg yolks, lemon juice, salt and cayenne pepper into a high powered blender and blend for 5 seconds until combined.
With the blender running on medium high, slowly stream in the hot butter into the mixture until it's emulsified and of desired consistency.
Pour the Hollandaise sauce into a small bowl and serve while warm.
Variation:
Sriracha Hollandaise: Blend in Sriracha to taste.
Notes
Reheating Hollandaise Sauce: Yes, Hollandaise can be reheated, but very carefully or it will split! Microwave at 20% power for 20 seconds at a time until sauce just begins to soften. Then reheat at 10 second intervals, stirring in between until sauce is of desired consistency.