- Heat oven to 220°C, 200°C Fan, Gas Mark 7.
- Prick the potatoes with a fork, place on a plate and microwave on HIGH (900W) for 6½ minutes. Turn the potatoes over and microwave for a further 3½ minutes.
- Transfer the potatoes to a baking sheet and brush with the oil. Season and place on the top shelf of the oven and cook for 20 minutes until the skin is crisp and the flesh is soft. Reduce the temperature to 200°C, 180°C Fan, Gas Mark 6, if the potato browns too quickly.
- Heat the remaining oil in a large non-stick frying pan over a medium heat and fry the onion for 5 minutes until soft. Add the garlic and Brussels sprouts, season and cook for a further 5 minutes until soft and golden.
- Remove the potatoes from the oven. Make a cross over each potato and split open slightly. Spoon over the Brussels sprout mixture and scatter with the blue cheese, to serve.