Preheat your oven to 400°F (200°C) and grease a 9x13-inch casserole dish.

Grate about three medium zucchinis and sprinkle with salt. Let sit in a colander for 10 minutes to draw out moisture.

After 10 minutes, squeeze out excess moisture from the grated zucchini using a clean kitchen towel.

In a mixing bowl, combine drained zucchini with two beaten eggs, 1/2 cup of grated Parmesan cheese, and 1 cup of shredded mozzarella cheese.

Press the zucchini mixture into the bottom of the casserole dish and bake for 20 minutes until set and lightly golden.

While baking, cook 1 pound of ground beef with one chopped onion in a skillet over medium-high heat for 5-7 minutes until browned and tender.

Stir in 1 cup of pizza sauce, diced green bell pepper, sliced mushrooms, dried oregano, and garlic powder. Let simmer for 5 minutes.

Layer the beef mixture evenly over the baked zucchini crust.

Sprinkle 1 cup of mozzarella cheese and 1 cup of cheddar cheese over the beef layer.

Return the casserole to the oven and bake for an additional 20 minutes until the cheese is bubbly and golden brown.

Allow to cool for 5-10 minutes before slicing and serving.