In a saucepan, melt the butter over low heat. Mix in the flour and continue to cook, stirring constantly, until the mixture turns a light brown colour, about 2-3 minutes.
Slowly start pouring in the milk, mixing constantly. Increase the heat to medium and cook the mixture for another 2-3 minutes or until thickened - the sauce should coat the back of the spoon.
Add the cheeses, stirring to melt. If you’re unable to melt in all the cheese, add a bit more milk - a tablespoon at a time - until the cheese is melted.
Meanwhile, in a large saucepan, add 2.5 litres of salted water and bring to a gentle boil. Cook the Mini Maccheroni for 2-3 minutes, draining it a minute before the al dente cooking time.
Drain the pasta and stir it into the sauce, reserving some cooked pasta on the side. If it seems too saucy, add the remaining Mini Maccheroni.
Place in a baking tray and top with breadcrumbs.