Preheat the oven 375 degrees. Coat a baking dish or oven-proof skillet with a thin layer of olive oil.
Heat the oil in a large skillet over medium-high heat. Add the spinach and cook until wilted, stirring frequently. Remove the pan from the heat and let the spinach cool.
When cool enough to handle, wrap the spinach in a kitchen towel or paper towels and wring out all the water. Transfer the spinach to a cutting board and coarsely chop. Set aside.
In a large bowl, combine the cream cheese, sour cream, ¾ cup of the mozzarella cheese, parmesan cheese, garlic, salt, and black pepper. Mix until well blended. Fold in the spinach.
Transfer the mixture to the prepared pan and top with the remaining ¾ cup of mozzarella cheese.
Bake for 20 minutes, until the cheese is golden, and the dip is bubbly. If desired, place the pan under the broiler and cook for an additional 1 to 2 minutes to brown the cheese further.
Top with chives and serve with crackers, pita, soft bread, and/or vegetables.
