Grease an 8 cup capacity (2 litre) baking dish with the butter
Finely chop garlic and sage together
Arrange a layer of white potato slices onto the base of the dish, overlapping slightly. Season with salt and pepper and sprinkle with a small amount of the chopped garlic, sage and cream. Add 2 tbsp. of the cheese over the potatoes
Next, top with a layer of sweet potato slices and continue layering with the garlic, sage, cream and cheese. Repeat layers of white potato and sweet potato until all of the vegetables have been used
Top the final layer with remaining cheese and season again with salt and pepper
Bake 55-60 minutes or until potatoes are cooked and top is golden. Stand for 5-10 minutes before serving
