Combine the cooled risotto with three-quarters of the parmesan, salt, garlic powder, Italian seasoning, and red pepper flakes in a large bowl. Stir everything together until it's evenly distributed throughout the rice. This forms the flavorful base for every bite.
Using a small cookie scoop, portion out the rice mixture and roll each scoop between your palms into a tight one-inch ball. Press firmly as you roll so the rice compacts and doesn't fall apart later. Repeat until all the rice is used.
Place the flour, whisked eggs, and breadcrumbs into three separate shallow bowls. Keeping them separate makes the coating process quick and mess-free. This setup is key to getting an even, crispy shell on every ball.
Dip each risotto ball first into the flour, then the egg, and finally the breadcrumbs, making sure it's fully covered at each stage. The flour helps the egg adhere, and the egg helps the breadcrumbs stick. Set the coated balls aside on a tray until you're ready to fry.
Pour vegetable oil into a heavy-bottomed pot until it reaches about two inches deep. Heat it over medium heat until it hits 365 degrees Fahrenheit. Getting the temperature right is essential for a crisp exterior without a greasy result.
Carefully lower three to four arancini balls into the hot oil at a time. Fry for one to two minutes, turning gently, until they're deep golden brown all over. Frying in small batches keeps the oil temperature steady.
Remove the fried balls with a slotted spoon and place them on a paper towel-lined plate to drain excess oil. Sprinkle the remaining parmesan while they're still warm. Serve them right away for the best texture.