Tip the potatoes into a large saucepan, cover with cold water and add the salt.
Cover with a lid and bring to the boil. Simmer for 12-15 minutes until tender when pierced with a knife.
Drain and then mash the potatoes until smooth using either a masher, ricer or by passing the potatoes through a sieve, adding two-thirds of the butter.
Heat the remaining butter in a large frying pan and fry the cabbage for 2-3 minutes until nearly tender then add the spring onions and cook for a further minute. Take off the heat and leave to one side.
Meanwhile, heat the oil in a non-stick frying pan over a medium heat and add the sausages. Cook the sausages for 10-12 minutes, turning regularlyso that they cook evenly. Remove from the heat and keep warm.
In a saucepan, gently heat the cream and blue cheese.
When the mixture starts to simmer and the cheese starts to melt, stir well and then beat into the mashed potato.
Add the cabbage and spring onions to the potato mixture and mix well. Season to taste with a little salt and pepper.
Serve immediately with the venison sausages.