How to make
Cut the bacon into cubes and fry it in a non greased pan. Grate the parmesan. Cut the mozzarella into slices.
When the bacon is fried, reduce the heat, add the butter and wait for it to melt. Add the flour and stir constantly to avoid lumps. The mixture should have the consistency of a thick porridge.
Pour the milk in a stream over the edge of the pan and stir until the sauce is smooth and homogenous. Season with nutmeg, white pepper and salt and let it boil again and thicken enough. When it boils again, remove it from the heat.
Start arranging the lasagna. Place the Béchamel on the bottom of the dish. Arrange a thick layer of sheets on top. Cover again with sauce. Arrange the mortadella pieces. Again put Béchamel sauce and cover with the lasagna sheets. Arrange the mozzarella and cover with a final layer of sauce. Finish off with grated parmesan.
Bake the lasagna at 390°F (200°C) for an hour until it acquires a golden crust.