Preheat oven to 350°F (175°C).
Trim the zucchinis and slice them into 1/8-inch-thick ribbons using a mandolin or sharp knife. Lay slices on a baking sheet in a single layer and sprinkle with 1 tablespoon salt.
Bake the zucchini slices 10–15 minutes, until they begin to dry and lightly brown; remove and set aside to cool.
Increase oven temperature to 375°F (190°C).
In a large skillet over medium-high heat, heat 2 tablespoons olive oil. Add ground turkey, diced onion, minced garlic, 1 teaspoon salt, and a pinch of black pepper. Cook, breaking up the meat, until turkey is browned and onion is soft, then remove from heat.
In a bowl, beat together the ricotta and the egg, seasoning with a pinch of black pepper; set aside.
Spray a 9×13-inch baking pan with cooking spray. Spread half of the pizza sauce evenly over the bottom of the pan.
Layer half the cooked turkey evenly over the sauce, then top with half the zucchini slices, half the ricotta mixture, half the pepperoni slices, and half the grated mozzarella.
Repeat the layers once more with the remaining turkey, zucchini, ricotta, pepperoni, and mozzarella. Arrange chopped green pepper and slivered black olives on top, then sprinkle with grated Parmesan.
Cover the pan with foil and bake at 375°F for 45 minutes. Remove foil and bake an additional 10 minutes.
Broil on high 2–3 minutes to brown the top, watching carefully to avoid burning. Let stand 5 minutes before slicing and serving.