To accomplish this task, beat egg yolks separately in a bowl and slowly incorporate a hot butter sauce.
I found that treating the sauce like a custard helped me achieve the right consistency. If you don't have a _bain-marie_, it's recommended to heat the sauce in a jug and place it in a boiling water saucepan. This helped me keep the heat even and prevent the sauce from overheating.
The recipe also suggested adding a little essence of mushroom to the sauce if possible. I discovered that the trimmings of mushrooms could create a great essence, but mushroom ketchup is an excellent alternative too.
Overall, making a hot butter sauce may require some extra care, but with the right techniques and ingredients, it can be an excellent addition to any dish.
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