People say that hollandaise is difficult; do it Mary’s way and it’s not.
Whisk together two fresh egg yolks with a dash of white wine vinegar in a large heat-proof bowl.
Place over a saucepan of simmering water (do not to let the bowl touch the water) and whisk until lukewarm.
Add 100g/3½oz melted butter to the egg yolks very, very slowly, beating continuously. Once the mixture has thickened, remove from the heat and season with salt and pepper.
Get the recipe for Mary's eggs Benedict Florentine here.