There are countless variations of lasagne throughout Italy. What they all require is a layering of ingredients and flavors: Paper-thin sheets of fresh pasta are usually combined with ragù, bechamel, and cheeses—from mozzarella to scamorza, to a simple dusting of Parmigiano Reggiano.  My grandma’s version calls for béchamel sauce, her Tuscan ragù, mozzarella, Parmigiano Reggiano, and fresh pasta. Then, her secret ingredient: moderation. In the kitchen, I followed her layer after layer, learning the importance of balancing the ingredients, how to smear the béchamel and the ragù with a wooden spoon to cover the entire surface of the pan, without exaggerating the quantities. This makes a lasagna that is compact, crisp on the edges, and perfectly balanced, not too creamy nor too heavy. This is our festive dish, prepared for Christmas, Easter, birthdays, or family gatherings. We usually prepare it and bake it the day before. That gives the lasagna …