Preheat oven to 350 degrees. Grease a small baking dish (8x8 will do) with nonstick cooking spray.
Drain all water from defrosted spinach. If you don't have time to defrost, microwave the spinach in a covered bowl for 4 minutes, then drain.
In a medium bowl, mix together softened cream cheese, yogurt, parmesan, and most of the mozzarella cheese (reserve two or three tablespoons for the top). Mix in spinach, artichoke hearts, garlic, and seasonings until everything comes together.
Spread mixture evenly in greased dish. Top with reserved mozzarella. Bake for 20-25 minutes, until hot and bubbly.