Step 1: Preheat your oven to 400°F (200°C) for even cooking.
Step 2: Line a baking sheet with parchment paper for easy cleanup.
Step 3: In a mixing bowl, combine the melted butter, smoked paprika, Italian seasoning, brown sugar, salt, garlic powder, onion powder, pepper, and red pepper flakes (if using). Stir until well combined.
Step 4: Coat each chicken tenderloin generously with the seasoning mixture.
Step 5: Arrange the coated chicken tenderloins in a single layer on the prepared baking sheet.
Step 6: Bake for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F (75°C).
Step 7: Let the chicken rest for about 5 minutes before serving.