Drain artichokes and pat dry with paper towel. Place artichokes, egg yolks, mustard, vinegar, parmesan, garlic, oil and a pinch of salt in a tall jug (see note below for why). Pour in oil.
With your stick blender head on the bottom of the jug, blitz on high speed. As you start to see the emulsion forming, slowly raise the stick blender so the upper layers of oil get emulsified too.
Taste and season with extra salt if needed (this can help tone down any bitterness from the oil ) or a little extra vinegar if the flavour is too flat.
If the mayo is too runny, carefully add extra oil in a thin stream while mixing with the stick blender. This requires some dexterity. If too thick, stir in a little water using a spoon, one tablespoon at a time.
Notes
If your mayo splits or doesn’t form a creamy, thick emulsion, it’s OK! Just start again with a new egg yolk, vinegar, and mustard. Pour the split mayo on top in place of the oil and cross your fingers this time.The other secret is to use a tall jug or container so that the head of the stick blender is covered by the non oil components. This is critical for getting the emulsion to happen. If the vessel is too flat you won't get the right type of mixing to make the emulsion work.