Preheat the oven to 200C/400F/Gas 6.
To make the potato, in a large bowl toss the potato rounds in the olive oil and season well.
Heat a griddle pan until smoking.
Char-grill the potato medallions for two minutes on each side. Transfer to the oven and roast for 10 minutes.
Remove from the oven and place on an ovenware dish.
To make the cauliflower, in a large bowl mix together the yolks, cream, cheese and cauliflower. Season with salt and freshly ground black pepper.
Place the mixture over the sweet potato and return to the oven to cook for a further five minutes.
Serve in the ovenware dish.