You can bake this as a completely separate, stand-alone dish or you can finish the saddle of deer or any roasting joint on top of the potatoes for the last part of cooking, depending on the size of the joint.
8 medium-sized waxy potatoes, peeled and thinly sliced
3 medium onions, peeled and thinly sliced
2tbsp rapeseed oil
1ltr beef or game stock
A few sprigs of thyme, leaves removed
Preheat the oven to 200C/gas mark 6. Heat the rapeseed oil in a heavy-based saucepan or frying pan and cook the onions on a medium heat for 5-6 minutes, turning them regularly, until golden.
Next, take an ovenproof roasting dish and lay the sliced potatoes into it with the onions and thyme leaves and build up the layers; season every couple of layers with salt and pepper.
When all the potato is used up, pour over enough stock just to cover.
Bake in the oven for 45-50 minutes, brushing the top with some of the cooking juices every so often.