Cook the macaroni according to the packets instructions, drain and set aside.
In the meantime, heat the oil in a frying pan and fry the bacon until crispy, place on a piece of kitchen paper and set to one side.
To make the sauce, in a large saucepan, melt the butter over a medium heat. With a large hand whisk add the flour and whisk continuously for a minute. Top tip: I find using a large hand held balloon whisk you are less likely to have lumps.
Gradually whisk in the milk, a little as at time. Cook for around 10mins until thickened and smooth.
Remove from the hob, add the cheese and stir until its well combined and melted.
Pre-heat the grill on a medium heat.
Add the macaroni and bacon and combine together. Tip into an oven proof dish, sprinkle with extra cheese and place under the grill until cheese starts to melt and turns golden.
Serve immediately with some crispy iceberg lettuce and garlic bread.