Zucchini Lasagna

• Olive oil for cooking
• 4 lb. zucchini, cut lengthwise into 1/4-inch-thick slices
• Salt and freshly ground pepper, to taste
• 4 cups ricotta cheese
• 1 cup grated Parmigiano-Reggiano cheese
• 2 Tbs. chopped fresh tarragon
• 1/3 cup unsalted butter
• 1/3 cup all-purpose flour
• 5 cups milk, warmed
• Freshly grated nutmeg, to taste
• 1 1/2 lb. lasagna noodles, cooked until just tender
• 4 lb. tomatoes, peeled, seeded and coarsely chopped
• 1 lb. mozzarella cheese, shredded

Preheat an oven to 375ºF. Butter a lasagna pan. In a large sauté pan over medium heat, warm 1 Tbs. of the olive oil. Working in batches, add the zucchini, season with salt and pepper and cook until golden brown, 2 to 3 minutes per side. Transfer to a platter and repeat with the remaining zucchini; set aside.

In a bowl, combine the ricotta, Parmigiano-Reggiano, tarragon, salt and pepper and stir to combine; set aside.

In a saucepan over medium heat, melt the butter. Add the flour and whisk until smooth, then cook until fragrant, 2 to 3 minutes. Slowly whisk in the milk until smooth. Cook, whisking occasionally, until thickened, 3 to 5 minutes. Season with salt, pepper and nutmeg; set aside.

Cover the bottom of the prepared lasagna pan with a layer of lasagna noodles. Spread one-third of the ricotta mixture over the noodles. Spread one-third of the tomatoes over the ricotta mixture, then top with one-third of the zucchini. Pour one-third of the sauce over the zucchini. Repeat the layering twice, finishing with a layer of noodles. Sprinkle with the mozzarella cheese. Bake until the lasagna is golden and bubbling, about 50 minutes. Let stand for 10 minutes before serving. Serves 10 to 12.