Baked Spinach and Artichoke Dip

fat-free sour cream

freshly ground black pepper

garlic cloves, minced

artichoke hearts, drained and chopped

frozen chopped spinach, thawed, drained, and squeezed dry

block 1/3-less-fat cream cheese, softened

block fat-free cream cheese, softened

part-skim mozzarella cheese, shredded and divided (about 1 1/2 cups)

fresh Parmesan cheese, grated and divided (about 1/4 cup)