Fry the sausages in a pan with some oil until done and keep aside.
Preheat the oven to 205°C/400°F.
In a pan over medium heat, add the butter and when melted, add the flour and keep mixing swiftly until the flour is well combined. Keep mixing for about a minute until the flour gets cooked in the butter.
Start adding the warm milk little by little with one hand, while continuing to whisk it with the other. Make sure you keep mixing swiftly so there are no lumps formed.
Once all the milk is incorporated, keep stirring until the sauce thickens.
Add salt and pepper to taste.
Turn off heat. Add the grated mozzarella and cheddar cheeses into the hot sauce and keep mixing until the cheeses melt.
Pour the cheese sauce on to the cooked pasta in a bowl and mix well until all incorporated.
Pour the mac and cheese mix on to a baking dish and top it with a layer of breadcrumbs and a drizzle of olive oil.
Bake for about 20 minutes or so until the top becomes golden brown.
Delicious mac and cheese is ready! Enjoy!