In a bowl mix minced meat, minced mortadella, grated Parmesan, breadcrumbs.
Knead well, add eggs, salt and pepper and a big pinch of grated nutmeg.
Knead again and form the a long meatloaf.
Roll the meatloaf into the extra breadcrumbs then let it golden in a pan with hot olive oil.
Let it golden on all sides, pay attention not to broke the meatloaf.
In a bakeproof casserole melt butter then put in the meatloaf.
Bake at 356°F for about 30 minutes, rotate in halfway.
Wait until slightly cold before cutting slices.
To make the sauce: melt butter on low fire, add sifted flour and mix until you have a paste.
Add milk little by little mixing, avoid lumps.
Add a inch of salt and a pinch of nutmeg, bring it to a boil then turn off the fire: the sauce have to be quite liquid.
You can keep it in the fridge and heat right before serving the meatloaf.