Heat the grill to high. Heat a medium non-stick frying pan, add the chipolatas and fry for 3 mins. Add the bacon, turning occasionally, until it starts to crisp, about 5 mins more. Tip in the mushrooms and continue to cook for a further 3-5 mins. Drain any excess fat and move the ingredients so they are evenly spread out.
Season the eggs, then add to the pan, swirling to fill the spaces. Gently move with a fork for 2 mins over a low-medium heat until beginning to set. Scatter over the tomatoes, cheese, if using, and chives, then grill for 2 mins until set. Cut into wedges and serve with your favourite sauces.