Preheat oven to 200ºC (390ºF). Cook the macaroni in a saucepan of boiling, salted water for 10–12 minutes or until al dente. Drain and return to the pan. Add the milk, cream, cheddar, mustard, salt, pepper and spinach and mix to combine. Spoon into 4 x 1½ cup-capacity (375ml) ovenproof dishes, top with extra cheddar and bake for 10–15 minutes or until the cheese is melted and golden.