Preheat oven to 375°F. Grease a 9X13 pan and set aside.
Ensure that the spinach is completely thawed. Squeeze out the excess moisture from the spinach and set aside. (spinach holds a lot of moisture so make sure to squeeze out the excess so your dip isn’t watery as it cooks)
Drain the canned artichoke hearts and chop them into smaller bite-sized pieces and set aside.
In a large mixing bowl, beat the softened cream cheese until it's light and fluffy.
Next add the drained spinach, chopped artichokes, mayonnaise, sour cream, Parmesan cheese, 1 cup mozzarella cheese, minced garlic, salt, and black pepper to the bowl.
Mix until all the ingredients are well incorporated.
Transfer the dip ingredients into the greased 9x13 pan (or two 9 inch square pans) and sprinkle the remaining mozzarella cheese on top.
Bake for 25-30 minutes uncovered until heated through and bubbly. Broil for an additional 1-2 minutes to brown the top of the dip.
Let sit for about 5 minutes right out of the oven because it will be piping hot.