Begin by preparing the besciamella sauce by melting butter, adding flour, whisking and gradually adding milk until thickened. Season with salt, black pepper and nutmeg.
Roll the pasta sheets using a pasta machine or rolling pin, then cut into rectangular pieces.
Boil the pasta squares, then lay them flat on towels to cool.
In a mixing bowl, combine ragù, besciamella sauce and Parmigiano cheese.
Spread a line of the mixture along a pasta square, roll it up, and place in a baking dish.
Repeat with remaining pasta squares to create a layer in the dish.
Cover with ragù, besciamella sauce, and Parmigiano cheese.
Bake, uncovered, until the top is crispy and golden. Let it rest before serving.