Preheat the oven to 400F / 205c.
Peel and discard the outer layers of the garlic bulb, and cut the top off of the bulb.
Drizzle with oil, cover with foil and place in the oven for 30 minutes until it is soft. Set to one side.
While the garlic is roasting, peel and quarter the potatoes.
Place the potatoes in a large pot of salted water and bring to the boil.
Boil for about 15 minutes until they are fork tender. Let them steam for 5 minutes.
Heat the cream gently in a pot or heat in the microwave, just to warm it through.
Place the potatoes back into the pot, add in the warm cream and butter and squeeze in the roasted garlic.
Mash everything together, taste and adjust the seasoning and serve. Garnish with fresh parsley if you like.