Prepare Breading: Mix flour, panko, garlic powder, salt, and pepper in a shallow bowl.
Make Egg Wash: Whisk eggs and milk until smooth.
Bread Cheese: Dip mozzarella cubes in egg wash, coat with breadcrumb mix, then repeat for a double coating. Place on parchment-lined tray.
Freeze: Freeze breaded cubes for 15–20 minutes to prevent melting during frying.
Make Garlic Dip: Combine mayo, sour cream, parsley, lemon juice, garlic, salt, and pepper. Chill.
Heat Oil: Heat oil in a deep pan to 350°F (177°C).
Warm Marinara: Heat marinara sauce until warm.
Fry Cheese: Fry mozzarella cubes in batches for 2–3 minutes until golden, turning occasionally.
Drain: Drain on paper towels and sprinkle with salt if desired.
Serve: Plate sticks with garlic dip and marinara. Garnish with parsley and Parmesan if you like. Serve hot.