- 1/2 cup very cold butter, divided
- 2 egg yolks
- 1 1/2 tablespoons fresh lemon juice
- 1 1/2 tablespoons water
- 1 pinch ground cayenne pepper, or more to taste
- Combine 1/4 cup butter, egg yolks, lemon juice, and water in a saucepan over low heat. Cook, stirring constantly, until butter is melted, about 5 minutes. Add remaining 1/4 cup butter and continue to cook, stirring constantly, until butter is melted and incorporated, about 5 minutes. Season with cayenne pepper.