Squeeze any and all water out of the spinach. Discard the water released. In a medium bowl, combine the spinach, cream cheese, artichokes, Mozzarella, Parmesan, and garlic then mix well, using your hands if needed. Season to taste with salt.
NOTE: In not using the artichoke, you can replace this with an additional 120 grams of spinach, or cooked and chopped broccoli, or even cooked and chopped asparagus.
Fill chicken pockets with 1-2 tablespoons of the filling, spreading evenly with the back of the spoon or use your fingers to press it down. Reserve the leftover dip for the optional cream sauce, you should have exactly half left over.
NOTE: If not making the optional cream sauce, you can use the left over filling as a dip, or just cut the filling ingredients in half so there is no filling left over.
Seal with two or three toothpicks near the opening to keep the filling inside while cooking.
Heat 1 tablespoon of oil in a non stick pan over medium high heat. Add the chicken and cook until golden brown, carefully turn the chicken over and cook the other side until golden, covering pan with a lid, until cooked through, about 6 to 7 minutes per side. Transfer chicken to a warm plate to make the optional cream sauce. Or serve right away with pasta or rice if not making the optional sauce.