Line a baking sheet with parchment paper and set aside.
In a shallow dish, whisk together the flour, salt, and black pepper.
In a second shallow dish, whisk together the egg and milk.
In a third shallow dish, combine the panko bread crumbs, Parmesan, garlic powder, parsley, basil, oregano, thyme, and crushed red pepper flakes.
Working with one cheese stick at a time, coat each piece in the flour mixture and shake off the excess.
Dip the cheese stick into the egg mixture, then coat it in the breadcrumb mixture, pressing gently so the coating sticks.
Repeat the egg and breadcrumb coating one more time on each stick for a thicker crust.
Place the coated mozzarella sticks on the prepared baking sheet.
Freeze for at least 1 hour.
Heat about 2 inches of oil in a large pot over medium heat until it reaches 350°F.
Fry the mozzarella sticks in batches of 4 or fewer, turning occasionally, for about 2 minutes or until golden brown and crisp.
Transfer to a paper towel-lined plate and lightly sprinkle with salt if desired.
Serve immediately with marinara sauce.

For the Marinara Sauce

Heat olive oil in a small saucepan over medium-high heat.
Add the minced garlic and sauté for 1 to 2 minutes until fragrant.
Stir in the crushed tomatoes, basil, oregano, and salt.
Reduce heat to medium-low and simmer for 10 minutes, stirring occasionally.
Add crushed red pepper, if using, and simmer 1 more minute.
Serve warm with the mozzarella sticks.