Zucchini and Country Bread Lasagna - Lidia

Ingredients

• For the Zucchini
• 2 pounds firm, unblemished zucchini (6 small or 4 medium)
• 1/2 teaspoon salt
• 2 tablespoons extra-virgin olive oil
• For Assembling the Lasagna:
• 2 tablespoons soft butter, for the baking pan
• 12 or so day-old slices of country bread (from a 1-1/2 pound loaf)
• 6 cups tomato sauce (see here)
• 2 cups grated Parmigiano-Reggiano or Grana Padano