Preheat the oven to 375°F (190°C).
In a large skillet, heat the olive oil over medium heat. Add the shredded cabbage and sauté for about 5-7 minutes, until it becomes tender. Remove from heat and let it cool slightly.
In a mixing bowl, combine the ricotta cheese, mozzarella cheese, Parmesan cheese, chopped green onions, eggs, garlic powder, onion powder, salt, and black pepper. Mix until well combined.
Stir in the sautéed cabbage until evenly distributed.
Pour the cabbage and cheese mixture into the pre-made pie crust, spreading it evenly.
Bake in the preheated oven for 30-35 minutes, or until the pie is set and the top is golden brown.
Allow the pie to cool for 10 minutes before slicing and serving.