Combine the spinach, artichoke hearts, mayo, parmesan cheese, plain greek yogurt, 1 cup of mozzarella, and garlic powder in a large bowl, mix until evenly combined. Pour into a 9" pie pan or small oven safe dish. Top with remaining mozzarella cheese. Bake for 20-25 minutes or until bubbly in center and cheese is slightly browned.
Serve hot with slices of crusty bread or crackers. Enjoy!