Posted by @CrabbyTheCrabster:
Easy (stick blender) Hollandaise Sauce
Ingredients
115g butter (I use salted)
2 large egg yolks
1 tbsp lemon juice (some recipes use vinegar or half water half lemon juice)
Melt the butter gently in a small pan until it's foaming. If you can skim off the white stuff, do so, otherwise let the milk solids settle at the bottom as much as possible.
Put the egg yolks and lemon juice in a container just wider than the head of the stick blender (they usually come with a tall narrow jug thing for this). Whizz them with the stick blender until pale and opaque (30 - 60 secs).
If possible, put the container on a grippy surface or wrap a tea towel round it, as you need three hands otherwise - one to hold the blender, one to pour the butter and one to stop the jug whizzing round with the blender! If someone is there to hold the container, that's the easiest thing.
When your butter is completely melted and the white bits (milk solids) are at the bottom, turn of the heat, turn on the blender and pour the melted butter very slowly into the egg yolks, whizzing the whole time. Move the stick blender up and down a bit to incorporate it all. It should be a tiny steady stream of butter like when you make mayonnaise.
Pour almost all of the butter in but leave the last bit that's got the milk solids in.
It only takes a minute or two, so leave it til everything else is ready. You can keep it warm for a little while (put the jug in a bowl of warm water) but it's best eaten immediately and doesn't reheat. It's rather delicious eaten cold (or from fridge) the next day though, straight from the jug.