Mac & cheese with spinach and smoked tuna piquant

Open the tins and save the tuna oil for the cooking. Cook the conchigliette according to the package directions, in plenty of salted boiling water. In another pot add the tuna oil, butter and flour, and whisk for 2-3 minutes until the mixture turns into a paste, and has a light golden color. Add a cup of the pasta cooking water and stir. Gradually pour in the milk and continue stirring until sauce begins to thicken. Remove from heat, add the mozzarella, tuna, pasta, and stir. Transfer to a baking pan, sprinkle with rusk crumbs, and bake in preheated oven at 200°C for 20′, until golden and well crusted.