Preheat the oven to 350°F (180°C). Place a wire rack inside a rimmed half-sheet baking pan.
Remove the chicken legs from the packaging, pat them dry thoroughly with paper towels, and set aside.
In a small microwave-safe bowl, melt the butter and set aside to keep 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 until evenly blended.
Brush a generous coat of melted butter over each chicken leg.
Working one at a time, press the seasoned flour mixture onto each buttered leg until evenly coated, using your hands to help the coating adhere.
Arrange the coated legs on the prepared rack with space between them to allow hot air to circulate.
Bake on the middle oven rack for 35 minutes, until the chicken is cooked through and the coating is crisp.
Remove from the oven and let rest at least 10 minutes before serving.
