Cook the pasta in a saucepan of salted boiling water according to the packet instructions until al dente.
Meanwhile, put the eggs in a small saucepan and just cover with cold water. Bring to the boil, then reduce to a gentle simmer and cook for 4 minutes (once the water boils the eggs will usually start to move around).
Roll up the ham and slice it as thinly as possible. Meanwhile, make the mustard dressing. Mix together the parsley, mustard, lemon juice, sugar, oil and a little salt and pepper in a bowl.
Drain the eggs, rinse in cold water, then crack the shells and peel away once cool enough to handle.
Add the spring onions to the pan of pasta 30 seconds before the end of the cooking time, then drain and return to the pan. Stir in the ham and the mustard dressing and pile on to warm serving plates. Shell and halve the eggs and serve on top.