Preheat the oven to 350°F (180°C). Place a wire rack inside a rimmed baking sheet and set aside.
Remove the chicken legs from their packaging and pat them dry with paper towels; set aside.
In a small microwave-safe bowl, melt the butter and keep it warm.
In a medium bowl, combine the flour, chili powder, paprika, garlic powder, onion powder, cayenne, cumin, kosher salt, black pepper, and brown sugar; mix well.
Brush each chicken leg with a generous coat of melted butter.
Using your hands, press the seasoned flour mixture onto each buttered chicken leg until evenly coated.
Place the coated legs on the prepared rack with space between them to allow air circulation for crisping.
Bake on the middle oven rack for 35 minutes, or until the chicken is cooked through and the skin is crisp.
Remove from the oven and let rest at least 10 minutes before serving.