Lasagne Bolognese with Spinach

1.Heat oil in a 12- to 14-inch heavy skillet over medium heat until it shimmers.

2.Cook pancetta, onion, carrot, celery, and garlic, stirring occasionally, until vegetables are golden and softened, 12 to 15 minutes.

3.Add beef and cook, stirring occasionally and breaking up any lumps, until meat is no longer pink, 6 to 10 minutes.

4.Stir in wine, milk, tomato paste, thyme, 1/4 teaspoon salt, and 1/4 teaspoon pepper.

5.Simmer, uncovered, stirring occasionally, until most of liquid has evaporated but sauce is still moist, about 1 hour.

6.Put spinach in a kitchen towel (not terry cloth) and twist to squeeze out as much moisture as possible.

7.Whisk together ricotta, eggs, parmesan, nutmeg, 1 1/4 teaspoon salt, and 1 teaspoon pepper.

8.Transfer 1 1/2 cups ricotta mixture to another bowl and whisk in 1/4 cup milk; set aside.

9.Whisk spinach into remaining filling with remaining 1/2 cup milk.

10.Preheat oven to 375°F with rack in middle.

11.Soak noodles in a bowl of very warm water until pliable but not softened, 3 to 5 minutes.

12.Place on a kitchen towel (it’s important not to pat noodles dry).

13.Spread 1 1/2 cups bolognese sauce in a 13-by-9-inch baking pan and sprinkle with 1 tablespoon parmesan.

14.Cover with 3 noodles, leaving space in between.

15.Spread half of spinach filling on top, then 1 cup bolognese sauce, and top with 1 tablespoon parmesan and 3 noodles; repeat.

16.Top with remaining bolognese sauce, 1 tablespoon parmesan, and remaining 3 noodles.

17.Pour reserved remaining 1/4 cup parmesan.

18.Cover pan tightly with parchment paper and foil (or just buttered foil) and bake 50 minutes.

19.Remove foil and bake until top is browned in spots, about 15 minutes more.

20.Let stand 15 to 30 minutes before cutting.