Whisk together 1 cup buttermilk, 1 large egg, 1/2 tsp salt, and 1/4 tsp black pepper. Submerge 1.5 lbs chicken tenderloins in the mixture and refrigerate for at least 30 minutes.

Whisk together 1 cup flour, 1/2 cup cornstarch, 1 tsp baking powder, 1.5 tsp garlic powder, 1.5 tsp onion powder, 1 tsp smoked paprika, remaining 1/2 tsp salt, remaining 1/4 tsp black pepper, and 1/2 tsp cayenne in a wide shallow bowl.

Lift each tenderloin from the buttermilk, shake off excess, and press firmly into the dry batter on both sides. Rest coated strips on a wire rack for 10 minutes.

Heat neutral oil to a depth of 2 inches to 350°F (175°C). Fry in batches of 3 to 4 strips for 5 to 6 minutes, turning once, until deep golden and the internal temperature reads 165°F (74°C). Transfer to a wire rack between batches.

Stack on a platter, dust with a pinch of smoked paprika, and serve with ranch dressing alongside.