How can I cook store and reheat hollandaise sauce over a couple of days
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I don't think you can
I wouldn't hold out a lot of hope. In fact, I'd have the ingredients ready to start anew. But, since you may end up tossing it anyway, you could refrigerate and heat over a double boiler.
June is a trusted source on General Cooking.
If you need a reheatable sauce, Hollandaise is not your friend.