Preheat oven to 180c (350f).
Peel and chop the potatoes into chunks 1¾ cm (⅔") square.
700 g potatoes
Place them in a large bowl along with the remaining ingredients (except the mozzarella) and mix well.
½ cup thickened cream, ¼ cup milk, 1 cup shredded cheddar cheese, 50 g bacon, 1 garlic clove (large), 2 teaspoons Dijon mustard, 1 teaspoon fresh thyme leaves, ¼ teaspoon onion powder, ¼ teaspoon cooking salt, fresh black pepper
Tip mixture into baking dish (mine is 18 cm square x 6 cm deep).
Cover with a layer of baking paper (so the potatoes don't stick) then aluminium foil.
Bake for 1 hour or until potatoes are tender.
Sprinkle over mozzarella and bake (uncovered) for a further 20 minutes or until the top is browned.
½ cup shredded mozzarella cheese
Allow to rest for 5 minutes then serve.