Using a mandolin or knife, slice each zucchini, lengthwise into thin ⅛” slices. Lightly sprinkle each one with a little kosher salt and pepper. In a large skillet over medium-high heat, add the olive oil until hot. Add the zucchini in single layer batches and fry/sautè on each side for a total of about 30 seconds. Remove the zucchini to a paper towel-lined plate and set aside.

In a saucepan or medium skillet over medium heat, melt the butter. Whisk in the flour and turn the heat to medium-low. Cook for just a couple minutes until the smell of raw flour is gone, but do not brown the flour creating a blonde roux. Carefully add the milk about a half cup at a time while whisking to prevent lumps. Once all of the milk has been added and the sauce isn’t lumpy, add the bay leaf, nutmeg, and a pinch of kosher salt and pepper (you now have a bèchamel sauce). Cook for about 5 minutes, then remove the bay leaf. Stir in the cup of parmesan cheese creating a mornay sauce. Stir until the sauce is smooth and taste for seasoning. Set aside.

Preheat the oven to 375°F. Combine 1 cup of the parmesan cheese with the panko breadcrumbs in a small bowl and set aside. In your baking dish, spoon a thin layer of tomato sauce (sugo di pomodoro) on the bottom of the dish. Layer zucchini to cover the sauce. Add a layer of the creamy parmesan sauce, sprinkle with a little more parmesan cheese and add a few torn basil leaves. Add a layer of the sugo and repeat the process 1-3 more times, depending on how deep your baking dish is. Once assembled (the top layer can be zucchini or tomato sauce), sprinkle the top with the parmesan cheese, some torn mozzarella and top with the panko mixture.

Bake uncovered for about 20-25 minutes. The dish should be bubbling around the edges and the middle should be hot throughout (read at least 165°F in the center if using a thermometer). Turn your oven to broil on high for about 2-3 minutes, or until you see some browning on the top layer of mozzarella and breadcrumbs. Remove from the oven and allow to cool for about 10 minutes before cutting into it. Spoon onto plates or bowls and serve!