Heat the olive oil in an ovenproof casserole dish. Then gently fry the onion, pepper and garlic until soft. Add the mushrooms and continue cooking for two minutes. Stir in the rice and cook for another minute.
Remove from the heat and add the parsley, stock, peas and salmon, stirring well.
Meanwhile, cook the butternut squash in boiling water until tender, then add to the risotto mix. Cover and bake in the oven for 20 minutes.
Remove from the oven, uncover and sprinkle cheese over the top, before returning to the oven uncovered for another five minutes, or until cheese is golden brown. Serve.