Cut each piece of string cheese into quarters, place the pieces on a baking sheet, and freeze for at least 8 hours, or overnight.
In a small bowl, beat the egg. Put the flour in a second small bowl. In a third medium bowl, combine both the seasoned bread crumbs, panko, Parmesan and parsley flakes.
Line a baking sheet with parchment paper. Dip the frozen cheese in the flour, shaking off any excess, then into the egg, and lastly coat with bread crumb mixture. Put the breaded cheese on the baking sheet. Freeze the breaded cheese for at least 1 hour (this is a must or they will melt in the oven before browning).
Preheat oven to 425°F. Spray the frozen cheese bites with a little bit of olive oil spray. Bake for 3 minutes, turn them over, and bake until melted inside and golden on the outside, watching them closely so the cheese doesn't come out of the breading, about 2 minutes. Serve immediately as baked mozzarella harden more quickly than fried.