First, make the hollandaise sauce. Mix the ¼ tsp vinegar and the yolk from the separated egg in a small bowl or beaker. While the buttersoft is still warm, using a stick blender, blend the egg yolk while slowly drizzling in the melted buttersoft. Once you’ve finished adding the buttersoft, blend the sauce for another minute or so, until thick.
Bring a pan of water to the boil over a high heat then reduce to a low simmer. Add the tablespoon of vinegar and gently break the eggs into the water. Cook for 1½ minutes. Remove with a slotted spoon onto kitchen paper.
Meanwhile, toast the muffin halves. Top with the Parma ham and poached eggs. Pour over the hollandaise sauce and serve sprinkled with chives.