Ensure that your frozen chopped spinach is fully thawed. Squeeze out any excess moisture using a clean kitchen towel or paper towels to prevent soggy cheese balls.
In a large mixing bowl, combine the thawed spinach, ricotta cheese, sour cream, shredded mozzarella, and shredded Parmesan. Add the large egg, salt, onion powder, garlic powder, Italian seasoning, and crushed red pepper flakes. Stir until well combined.
Using your hands, take small portions of the mixture and roll them into balls about 1 inch in diameter. Place the formed balls on a cookie sheet lined with parchment paper.
In a shallow dish, mix the all-purpose flour with the additional salt. In another shallow bowl, combine the dry bread crumbs with a sprinkle of salt.
Roll each cheese ball first in the flour mixture, shaking off any excess, then dip it in the bread crumbs to coat evenly, creating a crispy exterior when fried.
In a large skillet, heat about 1 inch of vegetable oil over medium heat. Carefully fry the cheese balls in batches, about 3-4 minutes per side, until golden brown and crispy. Transfer to paper towels to drain excess oil.
Serve hot with pizza sauce for dipping and enjoy the cheesy, flavorful bites!