Preheat the oven to 180Fan/200*C and line a baking tray with parchment paper. Add on the squash, cut-side up and rub all over with olive oil, salt and pepper. Roast for 40-50 minutes until tender and the outside is crisp. Take out the oven.
After 30 minutes, prepare the balsamic sprouts: toss everything together and roast on a line baking tray for 30 minutes.
Meanwhile, make the filling. Cook the quinoa/bulgar wheat according to packet instructions and drain. Heat a frying pan with 1 tbsp olive oil and add the mushroom and garlic. Fry for 10 minutes until really soft and all the juices have been released. Add in the fresh thyme, rosemary, chestnuts and dried cranberries.
Scoop out the seeds from the squash and discard them. Scoop out some of the flesh to make a larger cavity but leave a good edge of squash. Mash the flash with a fork and add into the mushroom frying pan with the cooked quinoa/bulgar wheat and tamari soy sauce. Season with salt and pepper. Stuff the filling into both halves of the squash, making it really compact (you may have extras). Place one half on top of the other and secure with string. Roast for 10 more minutes.
Serve the stuffed squash with any leftover filling, the balsamic sprouts and some pomegranate.