2 tablespoons Swiss chard, rinsed with stems removed, chopped
6 yellow onions, sliced thin
4 tablespoons unsalted butter
1 medium shallot, chopped
4 garlic cloves, chopped fine (Save 1 tablespoon)
5 sprigs thyme, chopped
4 tablespoons all-purpose flour
4 cups milk, warmed
½ cup grated Asiago cheese
¼ teaspoon nutmeg
4 tablespoons regular olive oil
1 handful toasted pine nuts
Freshly ground pepper and salt, to taste
2 teaspoons sugar
1 pound pasta sheets
Preheat oven to 400Â°F.
Melt the butter in a heavy-bottomed saucepan. Add shallots and sweat them until translucent, 3 to 5 minutes. Add garlic and thyme sprigs; cook, 1 minute. Stir in the flour and cook, stirring constantly until the flour cooks and bubbles a bit (donâ€™t let it brown) â€” about 2 minutes. Add the warm milk, continuing to stir as the sauce thickens. Bring to a boil. Add salt and pepper to taste, lower the heat, and cook, stirring for 2 to 3 minutes more. Add fresh nutmeg and remove from the heat. Strain sauce through fine mesh strainer and then let cool while you prepare lasagna. This constitutes the BÃ©chamel sauce.
In large sautÃ© pan, heat 1 tablespoon oil over medium heat. Add reserved 1 tablespoon garlic and cook, until fragrant, 30 seconds. Add Swiss chard and cook until tender, stirring often, about 5 minutes. Transfer chard to medium bowl, and season with salt and pepper. Set aside. Wipe out skillet, heat remaining 3 tablespoons olive oil over medium heat. Add onions and cook, stirring, until onions begin to brown all over, about 15 minutes. Sprinkle with sugar and stir. Cook, stirring, until deep amber in color, about 20 minutes more. Set aside. This constitutes the layer of caramelized onions.
Lightly oil a 9 x 13-inch baking dish or coat with nonstick cooking spray. Coat bottom of prepared dish with ½ cup of sauce. Layer bottom with a single layer of noodles. Spread half the chard over the noodles. Add another layer of noodles, arrange caramelized onions on top, and sprinkle with salt and pepper. Spread another ½ cup sauce over all. Add another layer of noodles, followed by the remaining chard mixture. Finish with remaining noodles and sauce. Sprinkle with Asiago cheese.
Loosely cover baking dish with aluminum foil. Bake lasagna for 30 minutes. Uncover, bake 10 to 15 minutes more, or until lightly browned and bubbling. Let stand for 10 minutes before serving.