1. Preheat the oven to 180°C.
2. Wrap the garlic bulb in foil and bake it for 20-25 minutes, until the garlic is soft and squidgy. Heat the olive oil in a pan and sauté the onions in an ovenproof pan until soft and golden, this will take a good 10-15 minutes.
3. Once brown, push to one side of the pan and add the sausages and brown evenly. Then add the brandy and de-glaze the pan. Add the balsamic vinegar, and then put the pan in the oven.
4. Cook it until the onions are beautifully caramelised and the sausages are cooked through, this will take about 20 minutes.
5. For the mash, peel and dice the potatoes and put them in a large pan of salted water, bring it to the boil and turn down the heat and simmer it for 20 minutes until the potatoes are tender.
6. Drain the potatoes and leave them to steam for about 5 minutes. Put the potatoes through a ricer and put them back into the pan.
7. Bring the potato together with a spoon, squeeze the roasted garlic in and season with salt and white pepper. Add the extra virgin olive oil until the mash is rich and glossy.
8. For an extra bit of luxury, add a drizzle of truffle oil to finish.