Greens and Cheese Vegetable Lasagna

Name: Greens and Cheese Vegetable Lasagna
Ingredients: 3 tablespoons unsalted butter; 3 tablespoons all-purpose flour; 3 cups whole milk, warmed; 2½ cups grated Parmesan; Kosher salt, freshly ground pepper; 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