Start by preparing the béchamel sauce:

Melt the butter and gradually add the flour. Once you have a thick, smooth mixture (a sort of dough), add the milk gradually while still on the heat and stir. Add the spices and continue stirring until you have a smooth mixture that is not too runny.

Cut the mozzarella and speck into pieces and cook the zucchini in a pan with a drizzle of oil.

Start assembling the lasagna:

Spread a layer of béchamel sauce on the bottom, add a layer of lasagna noodles, speck, mozzarella, zucchini, Parmesan cheese, and more béchamel sauce, then cover with another layer of lasagna noodles. Repeat until the entire baking dish is filled.