Preheat the oven to 180°C.
Quarter the new potatoes, skin still on, and add to a frying pan to sauté for 10 minutes until golden and partially cooked through.
Peel and slice the onions, then fry in another pan with the oil for a few minutes. Take the leaves off the thyme and chop, adding to the cooking onions.
Cut the bacon into strips and tip into the pan as well for a minute or two.
Peel the outer leaves off of the brussel sprouts and wash well. Grate the brussels using a food processor or slice thinly by hand. Hack the chestnut up into pieces.
Scatter all the prepared ingredients and crumbled blue cheese into a large roasting dish.
Splash in a little water then pour over the cream to almost cover the potatoes.
Sprinkle with the breadcrumbs and grated cheese and put into the oven for 20-25 minutes until it is golden on top and the potatoes are cooked, then sprinkle with parsley and serve with some simple steaming peas. Serves 4