In a bowl, whisk together buttermilk and hot sauce. Add the chicken tenders, making sure they’re well coated. Cover and refrigerate for at least 30 minutes, or up to 2 hours. This step helps the coating cling and keeps the meat juicy.
In a separate bowl, mix the flour, cornstarch, paprika, garlic powder, onion powder, cayenne, salt, and black pepper. This will be your crisp coating.
Remove the tenders from the buttermilk bath, letting excess drip off. Dredge them in the seasoned flour mixture, pressing gently so the crust adheres well. Place the coated tenders on a rack or plate as you finish each one.
Heat the oil in a deep skillet or Dutch oven to 350°F (175°C). Use enough oil for a shallow fry, about 1 inch deep. If you don’t have a thermometer, drop in a small crumb—if it sizzles, you’re ready.
Fry the tenders in batches, without crowding, for 3–5 minutes per side, until golden brown and an internal thermometer reads 165°F (74°C). Maintain the oil temperature as you go. Transfer cooked tenders to a rack set over a sheet pan to drain briefly.
Make the Nashville-style glaze: in a small saucepan, melt butter over low heat, then whisk in cayenne, brown sugar (if using), and a splash of vinegar for brightness. Simmer for 1–2 minutes until glossy. Remove from heat.
Brush the hot glaze over the freshly fried tenders or toss them gently to coat. If you prefer a lighter heat, brush the shot of glaze on the surface rather than bathe them.
Serve immediately. Classic accompaniments include white bread, dill pickles on the side, and a cooling slaw or a simple green salad to balance the heat.