1. Preheat the oven to 375°F and grease a 9×13-inch baking dish.

2. Bring a large pot of salted water to a boil and cook the elbow macaroni until just al dente. Drain and set aside.

3. Cook the bacon until crisp, then crumble it and reserve a small amount for topping.

4. In a large saucepan over medium heat, melt the butter.

5. Whisk in the flour and cook for 1 minute to form a roux.

6. Slowly pour in the milk, whisking constantly, and cook until the sauce thickens.

7. Stir in the garlic powder, onion powder, salt, and black pepper.

8. Reduce the heat to low and add the cream cheese, 2 cups of cheddar cheese, and 1 cup of mozzarella cheese. Stir until smooth.

9. Mix in the sour cream until fully incorporated.

10. Add the cooked macaroni, most of the bacon, and most of the green onions, then stir until evenly coated.

11. Transfer the mixture to the prepared baking dish.

12. Top with the remaining cheddar cheese, remaining mozzarella cheese, and reserved bacon.

13. Bake for 20 to 25 minutes, until hot, bubbly, and lightly golden on top.

14. Remove from the oven, let it rest for 5 minutes, then garnish with the remaining green onions and serve.