Make the béchamel sauce

1. In a saucepan, melt the butter over medium heat.
2. When the butter is bubbling nicely, add the thinly chopped spring onion and cook until translucent.
3. Then, add the flour all at once and stir energetically with a whisk until well incorporated about 2 minutes.
4. Add 1/3 of the milk and stir.
5. Add another 1/3 of the milk and keep stirring.
6. Add the rest of the milk and stir continuously for about 10 minutes until the sauce has thickened.
7. Add ¼ teaspoon of sea salt and a pinch of green pepper to taste.
8. Set aside while roasting the zucchini.

Roast the zucchini slices

1. Preheat the oven to 480°F (250°C).
2. Wash and cut the edges of the zucchini.
3. Using a mandolin or a sharp long knife, slice the zucchini lengthwise, into 0,2 inches (0,5cm) thick slices.
4. Line the zucchini slices onto a parchment-lined oven tray.
5. Brush each slice of zucchini with extra-virgin olive oil (or massage them with your fingers if you don’t have a baking brush).
6. Roast them in the oven until golden (about 15 minutes), then set them aside.
7. Repeat the process as you will need to make several batches to roast all the zucchini slices.

Assemble the Parmigiana

1. Turn the temperature of your oven down to 350°F (180°C ).
2. Grease a  10 x 13 inches (35 x 26cm) baking dish with extra-virgin olive oil.
3. Layer slices of roasted zucchini to cover the entire bottom of the dish.
4. Layer the creamy spring onion béchamel on top.
5. Add a generous layer of grated Caciocavallo Silano cheese.
6. Add a generous handful of fresh basil leaves.
7. Repeat the operation one time.
8. Finish by sprinkling all the grated Grana Padano cheese on top.
9. Cook in the oven for 40 minutes until golden and super fragrant.
10. Sprinkle a generous handful of fresh basil leaves just before serving. Enjoy immediately with a glass of chilled Fiano di Avellino!