Olive oil cooking sprayor an olive oil mister like this one
Marinara sauceor ranch dressing, for serving
Slice each piece of cheese in half crosswise so that you have 24 shorter pieces. Arrange the cheese in a single layer on a parchment-lined baking sheet or plate, then freeze until completely solid, about 1 hour.
Once fully chilled, place the flour in a shallow bowl (a pie dish works well). In a separate shallow bowl, whisk the egg, egg white, and 1 tablespoon of water until well combined. In a third shallow bowl, combine the whole wheat bread crumbs, panko, Italian seasoning, and garlic powder. Arrange the plates in a line (flour, eggs, breadcrumbs). Line a large, rimmed baking sheet with parchment paper.
Working no more than 2 to 3 cheese sticks at a time, dredge the frozen cheese sticks in the flour, shaking off excess.
Next, dip into the egg, then place in the bowl with the crumbs and lightly pat to coat (if you tackle too many cheese sticks at a time, the egg will freeze right onto the cheese and no longer be sticky enough for the crumbs to adhere). Place the breaded cheese sticks on the prepared baking sheet. Repeat the process with the remaining cheese sticks.
Place cheese back into the freezer for at least 2 hours or overnight (this is a MUST or the cheese will melt before the crumbs turn golden).
When ready to bake, preheat the oven to 400 degrees F and place an oven rack in the lower third of the oven. Line a large baking sheet with aluminum foil and coat with olive oil spray. Arrange the frozen cheese sticks on the sheet, leaving about 3/4 inch between each. Lightly coat the tops of the sticks with the oil.
Bake in the lower third of your oven for 6 to 8 minutes, until the cheese is heated through and the crumbs are golden. Let stand for 3 minutes and serve warm with marinara sauce for dipping. (I like to heat the sauce first.)
You can also prepare this recipe with a block of mozzarella cheese rather than string cheese. Simply cut the block into 4-inch by 1/2-inch sticks.
TO MAKE AHEAD AND FREEZE: Cheese sticks can be prepared through Step 5 and frozen overnight. For longer-term storage, transfer the frozen sticks to a ziptop bag and freeze them for several months. Bake directly from frozen.
TO STORE: Mozzarella sticks are best enjoyed immediately after making. You can try saving the leftovers in an airtight container in the refrigerator, then reheating them gently in a 350 degree F oven until warmed through.
Nutritional information has been calculated with half the amount of flour and bread crumb mixture, as not all of it is used, but you do need extra on each plate to be able to completely coat the cheese stick.