Place zucchini slices on paper towel or a cool rack, and lightly salt both sides. This process will extract excess moisture out of the zucchini to allow for a firmer zucchini layer in the lasagna. Let sit for 10 minutes, and blot excess moisture and salt with a paper towel.
4 medium zucchini
Preheat the oven to 375°F (190°C). Grease a 9x9-inch baking dish with cooking spray.
Heat olive oil in a large skillet over medium heat. Add the onion and garlic, and sauté until softened, about 3-4 minutes.
1 tbsp olive oil, 1 small onion, 2 cloves garlic
Add the ground chicken to the skillet, breaking it up with a spoon. Cook until browned and cooked through, about 5-7 minutes.
1 lb chicken
Stir in the marinara sauce, oregano, basil, salt, and pepper. Simmer for 10 minutes, stirring occasionally.
2 ½ cup marinara sauce, 1 tsp oregano, 1 tsp basil, 1/4 tsp salt, 1/8 tsp pepper
Meanwhile, in a medium bowl mix together ricotta cheese, egg, spinach, and basil until well combined.
1 cup ricotta cheese, 1 egg, ½ cup spinach, ¼ cup basil
Arrange a single layer of zucchini slices on the bottom of the prepared baking dish. Top with a layer of the meat sauce, followed by a layer of ricotta cheese. Repeat the layers, ending with a layer of sauce on top.
Sprinkle the mozzarella cheese evenly over the top.
1/2 cup mozzarella cheese
Cover the baking dish with foil and bake for 30 minutes. Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and lightly browned.
Let the lasagna cool for a few minutes before slicing and serving.