Preheat the oven to 200 degrees Celsius (390 degrees Fahrenheit)
Start by removing the stalk of the cauliflower and breaking the head up into small florets. Try to keep the florets uniform in size and not too big or chunky, otherwise they won't cook evenly.Place all of the florets into a large bowl.
In a large pot heat the olive oil on medium heat and add in the diced onions, celery and mushrooms and cook for approximately 5 minutes until the veggies have softened. Pour the cooked mixture into the bowl with the cauliflower and set aside.
Cook the sausage for approxiamtely 5 minutes until well cooked. Add the meat to the bowl along with the chopped sage, pecans, eggs and chicken stock. Season with salt and pepper and toss with your hands until well combined. Pour the stuffing into a baking dish and cover with tin foil. Bake for 20 minutes and then remove the tin foil and bake for another 10 minutes until the cauliflower is tender and the top becomes golden in colour. Serve warm with gravy.