Cut each mozzarella stick in half crosswise to make 24 pieces. Place on a baking sheet lined with parchment paper and freeze for at least 30 minutes.
Set up a breading station: In a shallow bowl, place flour. In another bowl, whisk eggs and milk. In a third bowl, combine crushed pretzels, garlic powder, and paprika.
Working with a few frozen cheese sticks at a time, coat each in flour, shaking off excess. Dip into egg mixture, then roll in pretzel crumbs, pressing gently to adhere. Return to baking sheet and freeze for another 15 minutes.
Pour oil to a depth of 2 inches in a deep pot or Dutch oven. Heat to 350°F (175°C).
Fry 6-8 sticks at a time for 1-2 minutes, turning once, until golden brown. Drain on paper towels. Serve immediately with marinara sauce or ranch dressing.
Tips
Freezing the cheese sticks before breading and after breading helps prevent the cheese from melting out during frying.
Crush pretzels in a food processor or place in a zip-top bag and crush with a rolling pin until fine.
Leftover sticks can be frozen after breading and fried directly from frozen, adding 1 minute to frying time.