1-Preheat your oven to 400°F (200°C): Preheat your oven to 400°F (200°C).
2-In a large bowl, combine the shredded: In a large bowl, combine the shredded zucchini and salt. Let it sit for 10 minutes to release excess moisture.
3-After 10 minutes, squeeze out as much: After 10 minutes, squeeze out as much moisture as possible from the zucchini using a clean kitchen towel or cheesecloth.
4-In the same bowl, combine the drained: In the same bowl, combine the drained zucchini, eggs, Parmesan cheese, and half of the mozzarella cheese. Mix well to form the crust mixture.
5-Grease a 9×13-inch baking dish: Grease a 9×13-inch baking dish. Press the zucchini mixture evenly into the bottom of the dish to form the crust.
6-Bake the crust in the preheated oven: Bake the crust in the preheated oven for 20 minutes, or until it is set and lightly browned.
7-While the crust is baking, in a: While the crust is baking, in a skillet, brown the ground beef with the chopped onion over medium heat until the beef is no longer pink. Drain any excess fat.
8-Stir in the pizza sauce, green bell: Stir in the pizza sauce, green bell pepper, mushrooms, oregano, garlic powder, and black pepper. Cook for another 5 minutes, stirring occasionally.
9-Once the crust is ready, spread the: Once the crust is ready, spread the beef mixture evenly over the zucchini crust.
10-Sprinkle the remaining mozzarella cheese and all: Sprinkle the remaining mozzarella cheese and all of the cheddar cheese over the top.
11-Return the casserole to the oven and: Return the casserole to the oven and bake for an additional 20 minutes, or until the cheese is melted and bubbly.
12-Remove from the oven and allow the: Remove from the oven and allow the casserole to cool for a few minutes before slicing and serving.