Cheesy Caramelized Onion & Spinach Lasagna

Directions

Bring a large pot of water to a boil.

Cook noodles until not quite al dente, about 2 minutes less than the package directions.

Drain, return the noodles to the pot and cover with cool water.

For the onion filling:

Meanwhile, heat 2½ tablespoons oil in a large skillet over medium heat.

Stir in onions and cook, stirring constantly, until golden brown and very soft, 25 to 30 minutes. (If they start to stick, stir in water 3 to 4 tablespoons at a time to prevent burning.)

Stir in mushrooms and cook, stirring, until just beginning to soften, 3 to 5 minutes.

Stir in wine and 1 teaspoon salt and continue cooking until most of the liquid is absorbed, 3 to 4 minutes.

Remove from heat, stir in black pepper.

For the spinach filling:

Put spinach, ricotta, basil and ½ teaspoon salt in a food processor and process until smooth.

For the white sauce:

Heat 2½ tablespoons oil in a medium saucepan over medium-high heat.

Stir in flour until bubbling, about 30 tio 35 seconds.

Slowly add in milk and ½ teaspoon salt and bring to a boil, whisking frequently.

Cook, whisking, until the sauce has the consistency of thick gravy, about 1 to 2 minutes

Stir in cheese and gently stir until it is melted.

Remove from the heat. (The sauce will continue to thicken as it sits.)

For assembling lasagna:

Preheat oven to 375°F.

Spray a 9-by-13-inch baking pan with cooking spray.

Drain the noodles and spread out on a kitchen towel.

Spread ½ cup white sauce evenly in the prepared baking pan.

Arrange a layer of noodles over the sauce.

Spread half of the spinach filling evenly over the noodles and top with one-third of the onion filling.

Spread another ½ cup white sauce evenly over the onions.

Repeat with another layer of noodles, the remaining spinach filling, half the remaining onion filling and half the remaining white sauce.

To finish:

Top with a third layer of noodles, spread the remaining onion filling over the noodles and then spread the remaining white sauce on top.

Sprinkle with walnuts and basil.

Bake until hot and bubbling, 30 to 35 minutes.

Allow to cool for a few minutes.

Serve warm.