France. Named Hollandaise not because it is Dutch but because Holland was considered the source of the finest butter in the 19th century. One of Auguste Escoffier's five mother sauces, it is the foundation of Sauce Bearnaise, Sauce Choron, and Sauce Maltaise.
Hollandaise is a warm emulsion of egg yolk and clarified butter, stabilised by the lecithin in the yolks, acidulated with lemon juice or reduction. It breaks easily and is one of the most technically demanding sauces in classical French cooking. The egg yolk must be cooked enough to stabilise the emulsion (65-70C internal temperature) but not so much that it scrambles. The butter must be added slowly while the yolks are whisked continuously.
- Bearnaise (hollandaise with tarragon reduction — the famous variation); Dutch advocaat-based zabaglione (same warm emulsified yolk base technique); Japanese egg custard sauces (creme anglaise is a cold-served version of the same emulsification principle).
Hollandaise is a component sauce — it serves eggs Benedict, asparagus, and fish. For eggs Benedict: Blanc de Blanc Champagne. For asparagus: Alsatian Riesling. The sauce itself is not the pairing unit — the dish it is served on is.