Ingredients

  • 6 tablespoons extra-virgin olive oil
  • 1 medium onion, chopped
  • 5 garlic cloves, minced
  • Kosher salt
  • Freshly ground black pepper
  • 6 tablespoons all-purpose flour
  • 6 cups whole milk
  • 12 ounces baby spinach
  • 12 no-boil lasagna noodles
  • 1 cup ricotta cheese

Method

  • Preheat the oven to 375F.
  • In a large heavy pot, heat the oil over medium high heat until hot.
  • Stir in the onion, garlic, 1 teaspoon salt and 3/4 teaspoon pepper, and cook, stirring, until golden, about 8 minutes.
  • Stir in the flour and cook, stirring, 1 minute.
  • Whisk in the milk and bring to a boil, whisking.
  • Boil 5 minutes, then stir in the spinach and cook until wilted, about 3 minutes.
  • Remove from the heat season sauce with salt and pepper to taste.
  • In a 3-to 3 1/2-quart lasagna dish spread 1 cup of the cheese sauce over the bottom.
  • Make layers of noodles and sauce finishing with a layer of sauce.
  • Dollop the ricotta over top of the lasagna.
  • Cover the lasagna dish with aluminum foil and bake until the filling is bubbling, about 45 minutes.
  • Uncover the dish and continue to bake until the cheese is browned, about 30 minutes more.
  • Let the lasagna stand 10 minutes before serving.