Every Italian muggle family has it own traditional lasagna. This is my humble one.
Lasagna seems to be a muggles food, there is no mention in Harry Potters as a food in the wizarding world. The only information I could gather about lasagna and J.K. Rowling’s world is that Harry Potter and the Philosopher Stone has been written in The Elephant House, downtown Edinburgh, where they serve also Italian food. Harry Potters adventures take place in the British wizarding world, I suppose in the Italian school of magic they have lasagna every Sunday. For the Italians lasagna is the traditional Sunday meal, every muggle family has its own recipe and this is my own. We like lasagna with a lot of béchamel sauce and Parmigiano but you can experiment also in the way my mum does: she melts a mozzarella in the béchamel so that the sauce is more thick with a much marked milky taste.

Ingredients:
Bolognese sauce (you can find the recipe here)
1 packet of egg lasagna (no pre cooking needed)
Parmigiano cheese at please
salt
For the Béchamel sauce
1/2 l. whole milk
30 grams butter
30 grams corn starch
Kosher salt, to taste
Pinch of ground nutmeg
Melt butter in a saucepan over medium heat. Add flour. Cook, stirring, with a wooden spoon, for 1 to 2 minutes or until mixture bubbles. Gradually stir in milk. Bring to the boil. Reduce heat to medium. Cook, stirring, for 4 to 5 minutes or until mixture thickens. Season with salt and nutmeg. Cool before you use it.
Assemble the lasagna
Preheath the oven at 180 C. To assemble, spread a few tablespoon of Bolognese sauce in the bottom of baking dish. Arrange the sheets of lasagna and pour over meat sauce. Spread with some spoon of béchamel sauce. Top with as much Parmigiano as you like. Repeat layers (at least 3), and top with remaining Bolognese, Béchamel and Parmesan cheese.
Bake in preheated oven for 30 to 40 minutes (depends on how many layers you have).
Is nice hot and warm!

