- 3 tablespoons unsalted butter
- 3 tablespoons all-purpose flour
- 3 cups whole milk, warmed
- 2½ cups grated Parmesan
- Kosher salt, freshly ground pepper
Lasagna And Assembly
- 12 ounces lasagna noodles
- Kosher salt
- ¼ cup olive oil, plus more for pans
- 4 garlic cloves, thinly sliced
- 2 bunches collard greens, thick stems removed, coarsely chopped
- 2 bunches Tuscan kale, thick stems removed, coarsely chopped
- Freshly ground black pepper
- 2 pounds ricotta
- 2 large eggs
- 1 tablespoon fresh thyme leaves
- 1 teaspoon finely grated lemon zest
- 8 ounces fresh mozzarella, torn into bite-size pieces
- Heat butter in a medium saucepan over medium until foaming. Whisk in flour and cook, whisking constantly, about 1 minute. Add milk 1 cup at a time, whisking to incorporate after each addition. Bring to a simmer and cook, whisking occasionally, until slightly thickened, 6–8 minutes. Remove from heat and add Parmesan, whisking until cheese is melted and sauce is smooth; season béchamel with salt and pepper.
Lasagna and Assembly
- Preheat oven to 350°. Cook lasagna noodles in a large pot of boiling salted water, stirring occasionally, 2 minutes less than package directions; you want them to be very al dente so they won’t become mushy when baked. Drain noodles and transfer to a lightly oiled baking sheet; turn noodles to coat (this will prevent them from sticking to one another and make them easier to handle).
- Meanwhile, heat ¼ cup oil in a large skillet over medium-high. Add garlic and cook, stirring constantly, until fragrant, about 1 minute. Add a few handfuls of greens and cook, tossing and adding more greens as they wilt, until all greens are tender, about 5 minutes; season with salt and pepper.
- Combine ricotta, eggs, thyme, and lemon zest in a medium bowl; season with salt and pepper.
- Lightly oil a 13×9″ pan. Arrange noodles to cover bottom of pan, cutting to fit as needed. Spread one-third of ricotta mixture evenly over noodles, then top evenly with one-third of cooked greens. Spoon one-quarter of béchamel over greens, spreading evenly to cover. Add another layer of noodles. Repeat layers 2 more times, starting with noodles and ending with béchamel. Top with a final layer of noodles, then spread with remaining béchamel. Scatter mozzarella over top.
- Bake lasagna until bubbling and beginning to brown on top, 45–50 minutes. Let cool at least 20 minutes before serving.