Preheat the oven to 200C/400F/Gas 6.
Pour the double cream and milk into a large saucepan and bring to a simmer.
Add the potato slices, butter and Stilton (reserving some to sprinkle over the top), garlic, salt and freshly ground black pepper and simmer gently for five minutes.
Spoon into an ovenproof dish and sprinkle with the reserved Stilton. Bake in the oven for 15 minutes, or until bubbling and golden-brown on top. Serve in the dish.