In a large pot, bring 4-6 cups of water to a rolling boil, add a pinch of salt and the package of macaroni until fully cooked. Drain and set aside. In a cast-iron frying pan on medium-low heat, add butter and garlic, stir for 1 minute.
Slowly stir in flour, mustard, salt and pepper until smooth; gradually whisk in milk, cream and beer. Bring to a boil and let cook 2 minutes until thickened. Reduce heat, adding 2 cups of the cheddar, all of the mozzarella and 1 tablespoon of parmesan until melted. Stir in drained macaroni and bacon, and top with the remaining cheese and breadcrumbs.
Bake uncovered at 400⁰F for 15-20 minutes until golden brown on top. Let stand for 5 minutes before serving.