In a large mixing bowl, combine chopped spinach, cream cheese, shredded mozzarella, sour cream, grated Parmesan, garlic powder, onion powder, salt, and black pepper. Mix until thoroughly combined and creamy, ensuring no clumps remain.

Cut the mozzarella string cheese sticks in half, creating shorter pieces. Take a spoonful of the spinach mixture and wrap it around each cheese stick, ensuring they are completely covered.

Set up three shallow dishes: one with flour, one with beaten eggs, and one with breadcrumbs. Dip each spinach-wrapped cheese stick first into the flour, then the egg, and finally coat it with breadcrumbs.

In a large skillet, heat vegetable oil over medium heat to 350°F. Add a few sticks to hot oil, frying for 2-3 minutes on each side until golden brown.

Remove the sticks with a slotted spoon and transfer to a plate lined with paper towels to drain any excess oil. Let cool slightly before serving.