1) Cook the spaghetti in plenty of salted water until tender and strain it.
2) In a large wok or skillet melt half of the butter over medium heat.
3) Add the sausages and fry them until cooked through and browned on all sides.
4) Transfer the sausages to a clean chopping board and slice them up.
5) Add the sliced sausages back to the pan together with the chopped spring onion. Fry for 3 minutes.
6) Add the cooked spaghetti, ketchup, mayo, hot chili sauce and the rest of the butter.
7) Stir and toss well. Add extra ketchup, chili sauce or butter to taste.
8) Divide the spaghetti over bowl and serve.