Start by preparing the sauce. In a small bowl, combine the buttermilk, cayenne pepper, and brown sugar. Mix well until the sugar is dissolved and set aside.
In a shallow dish, mix the flour, salt, black pepper, garlic powder, and paprika together for the dry coating.
In another shallow dish, place the beaten eggs. In a third dish, put the breadcrumbs.
Dip each mozzarella stick first in the flour mixture, ensuring even coating, then in the beaten eggs, and finally in the breadcrumbs, pressing to coat well. Repeat with all mozzarella sticks.
Once all sticks are coated, place them in the freezer for at least 30 minutes to firm up.
In a deep frying pan or pot, heat oil over medium heat, enough to submerge the sticks.
Carefully add a few mozzarella sticks at a time to the hot oil, frying until golden brown and crispy, about 2-3 minutes per side.
Using a slotted spoon, remove the sticks and drain on paper towels.
Quickly dip each hot mozzarella stick into the prepared spicy buttermilk sauce, then place them back on the paper towel.
Serve the Nashville Hot Mozzarella Sticks immediately while they are hot and crispy, with extra dipping sauce on the side.