Cornstarch (Best Option)
1 teaspoon per 1 tablespoon arrowroot powderCornstarch is a starch extracted from corn and has a similar thickening mechanism to arrowroot, gelatinizing when heated with liquids to create a viscous texture. It works well in Béarnaise Sauce because it thickens at relatively low temperatures and does not impart flavor, preserving the sauce’s delicate balance.
To use cornstarch effectively, mix it with a small amount of cold water to create a slurry before adding it to the sauce to avoid lumps. Avoid overheating the sauce after adding cornstarch, as excessive heat can cause it to break down and thin out.
Compared to arrowroot, cornstarch may produce a slightly less glossy finish and can be a bit heavier, but it will still yield a smooth, stable Béarnaise sauce suitable for classic presentation.