Basil-Spinach Pesto:
Combine spinach, basil, garlic, pine nuts, parmesan, lemon zest, juice, and salt + pepper in the bowl of a food processor. With the motor running, slowly add olive oil until emulsified; set aside.
Bechamel Sauce:
Heat butter in a medium saucepan over medium heat until melted and foaming. Slowly add flour and cook, whisking constantly, for 1 minute. Whisk in milk, ½ cup at a time. Bring the sauce to a boil, reduce heat, and simmer, whisking frequently, until the sauce thickens and is the consistency of cream. This will take about 8-10 minutes. Season with nutmeg and salt, to taste. Remove from heat and set aside
Lasagna + Filling:
Preheat oven to 350º Fahrenheit.
Prepare lasagna noodles according to the directions listed on the package, drain pasta, and lay noodles flat in a single layer on a clean dish towel or large sheet of wax paper.
In a large mixing bowl, combine ricotta, pesto, parmesan, and egg; set aside.
Line the bottom of the pan with ½ cup of the béchamel sauce.
Take about ¼ cup of the ricotta -pesto mixture and spread it evenly onto each lasagna noodle. Top each noodle with 1 zucchini slice and 2 tablespoons of béchamel sauce. Carefully roll the noodles up and place them in the prepared pan. Top the lasagna rolls with the remaining béchamel sauce and mozzarella cheese. Spray a large sheet of foil with cooking spray and cover the pan.
Place the pan in the oven and bake for 30 minutes. Remove the foil and bake for an additional 5 minutes, or until the cheese is melted on top. Remove from the oven and let sit for 5 minutes. Garnish with parsley. Serve warm. Enjoy!