Infuse the milk: Pour the milk into a saucepan with the onion, garlic cloves, bay leaf and star anise. Bring almost to the boil, remove from the heat, cover and leave to infuse for 30 minutes. Strain into a jug and discard the flavourings.
Heat the oven: Preheat to 200°C/180°C fan/Gas 6.
Make the sauce: Melt the butter in a large saucepan over low heat, stir in the flour and cook the roux for 1 minute. Gradually whisk in the warm infused milk until smooth, bring slowly to the boil whisking constantly, then simmer gently for 5 minutes. Off the heat, whisk in the Comté and Cheddar until smooth and season.
Cook the macaroni: Boil the macaroni in salted water until al dente, about 9 minutes. Drain, refresh briefly under cold water and drain again.
Toast the crumbs: Melt the butter in a frying pan, soften the garlic for a minute without colouring, then stir in the breadcrumbs and toast over low heat for about 8 minutes until pale golden, stirring so they don't catch. Stir in the parsley.
Assemble and bake: Mix the macaroni through the cheese sauce and pour into a large, wide gratin dish. Scatter the mozzarella over, then the Parmesan, then the toasted crumbs. Bake for 15 to 20 minutes until golden and crisp, and serve with a crisp salad.
