Preparation
Preheat the oven to 220°C, fan 200°C, gas 7. Empty the contents of the stuffing packet into a bowl, pour over 400ml of just-boiled water, stir and leave to stand for 5 minutes. Place in a greased oven dish and bake for 25-30 minutes, until golden and crisp on top. Set aside to cool.
Meanwhile, bring a large pan of salted water to the boil. Peel and finely slice the potatoes (about 3mm thick). Boil for 4 minutes, then drain through a colander and set aside to cool. Melt the butter over a low heat in the same pan.
Finely grate the parmesan and finely chop the leaves from the rosemary sprigs. Pour the cream into a bowl and stir in the rosemary, salt, 35g of the parmesan and some black pepper. Brush a 1.5l round ovenproof dish (22cm diameter x 6cm deep) with some of the melted butter. Take about a quarter of the potato slices and arrange in the base of the dish, slightly overlapping, but in an even layer. Brush with melted butter, then crumble over a third of the stuffing and spoon over about a quarter of the cheesy cream. Repeat these layers, finishing with the potatoes, butter and the remaining 15g parmesan.
Cover with foil, then bake for 1 hour. Uncover and bake for a final 15-20 minutes, until crispy and golden in colour. Leave to stand for 10 minutes, then slice into wedges to serve.
A cracker of an accompaniment for your festive centrepiece, these oozy sliced potatoes are layered with sage and onion stuffing and an indulgent parmesan cream.