Preheat oven to 350°F. Place zucchini in a large 15x10 casserole dish.
Sprinkle salt, pepper and half of the garlic powder on the zucchini. Bake 10 minutes.
Meanwhile, heat oil in a large, deep skillet over medium high heat.
Add lamb and cook until fully browned, about 5-7 minutes.
Add onion, bell pepper, minced garlic, and half of the Greek seasoning. Saute until softened, about 5 minutes.
Add rice and remaining seasonings along with a pinch of pepper. Cook, stirring well until the rice is no longer frozen.
Scoop the filling into the partially cooked zucchini. Bake for 10-15 minutes or until the zucchini reaches your preferred doneness.
Top with tzatziki and feta cheese and serve!
Enjoy!