You can but this ready made at all major supermarkets , but it really is simple to make it yourself. All you need is 10 minutes a good whisking arm and a little patience and what you end up with is a smooth, silky and rich hollandaise.
2 egg yolks
2 tablespoons water
2 tablespoons lemon juice
175g unsalted butter, cut into cubes
Salt and pepper to taste.
Simmer water until only just a simmer, add a large bowl on top ensuring no water is hitting the base of the bowl.
Add the 2 yolks and 2 tablespoons of water into the bowl and with a metal balloon whisk, continuously whisk for around 3 minutes until doubled in volume, thick and leaves a ribbon when you lift the whisk.
Start to add the butter a cube at a time and whisk until incorporated, continue a cube at a time until all the butter has been added.
Remove the bowl from on top of the pan and add the chopped parsley 2 tablespoons lemon juice and season. Stir well and serve.