Melt 4 tablespoons of butter in a small saucepan over low heat.

Ensure the butter does not brown.

In a medium-sized bowl, combine 4 egg yolks, 2 tablespoons of fresh lemon juice, salt, and freshly ground pepper.

Whisk the ingredients together until well combined.

Begin the tempering process by adding 1 teaspoon of the melted butter to the egg yolk mixture.

Whisk constantly to prevent curdling.

Gradually add the remaining melted butter, about 5 tablespoons in total, in a slow, steady stream while continuously whisking.

Transfer the tempered egg mixture to the saucepan.

Cook over very low heat for no more than 15 seconds, whisking constantly to prevent scrambling.

Continue cooking in 5-second increments, whisking constantly, until the sauce thickens to your desired consistency.

If the sauce becomes too thick, thin it with a few drops of warm water before serving.