Heat the grill to its highest setting. In a flameproof casserole dish or metal frying pan, melt the butter and fry the garlic for 2 mins. Add the spinach and cook until it wilts, about 2 mins. Pour in the milk and beer and bring to a gentle bubble. Add the macaroni and stir intermittently for around 20 mins until the pasta is cooked and covered in sauce.

Stir in the cheddar and half the mozzarella. When it starts to melt, sprinkle the remaining mozzarella on top and put it in the oven for around 7-10 mins or until browned on top and sensational underneath.