Preheat oven to 375 degrees F (190 degrees C) and grease a 9 by 9 baking dish.

In a large skillet over medium heat, cook the ground turkey for 6 to 8 minutes, breaking it up with a spoon, until browned.

Stir in the garlic powder, salt, and pepper. Add the spinach and cook for 2 to 3 minutes until wilted.

Reduce heat to low. Stir in the softened cream cheese until fully melted and combined with the turkey mixture.

Remove from heat and let the mixture cool for 5 minutes. Stir in the beaten egg and half a cup of the cheddar cheese.

Transfer the mixture to the prepared baking dish. Top with the remaining half cup of cheddar cheese.

Bake uncovered for 20 to 25 minutes, or until bubbly and golden on top.

Let rest for 10 minutes before slicing and serving.