Fry the bacon in a pan until crisp and then remove and set aside.
Dice the shallot and slice the leeks, sauté these in the bacony oil for about 5 minutes before adding the garlic.
Cook for another minute and then add flour. Cook this until no white parts remain, about 2 minutes.
Pour in the milk, stirring constantly and add the stock cube. Mix well until it becomes slightly thick and then add your cooked pasta and bacon pieces.
Mix well and top with fried breadcrumbs
