Preheat your oven to 400°F (200°C).

Shred the zucchini and toss it in a bowl with salt. Let it sit for about 10 minutes.

Drain the zucchini by twisting it in a clean kitchen towel to remove moisture.

In the bowl with drained zucchini, add the eggs, Parmesan cheese, and half of the mozzarella. Stir until well combined.

Grease a 9x13-inch baking dish and press the zucchini mixture into an even layer.

Bake the crust for about 20 minutes until set and lightly browned.

In a skillet over medium heat, brown the ground beef and onion for 7-10 minutes.

Add the pizza sauce, green bell pepper, mushrooms, oregano, garlic powder, and black pepper to the skillet. Simmer for 5 minutes.

Spread the beef mixture evenly over the baked crust.

Top with remaining mozzarella and cheddar cheese.

Bake again for 20 minutes until the cheese is melted and bubbly.

Let the casserole cool for 5-10 minutes before slicing.