Fry the bacon until crisp then add the olive oil. Tip in the flour and cook out for 1 minute then slowly pour in the milk and beer. Stir until it thickens slightly then season with salt, pepper and garlic powder.
Add the parmesan and cheddar and stir to melt into the sauce. Now add your macaroni and toss to coat. Set aside.
Cut the top off your bread boule. Pull the centre out and discard. Now tip your macaroni cheese into the cavity and top with more parmesan and breadcrumbs.
Brush the exterior of the bread and the sliced piece with garlic butter.