Preheat the oven to 425°F. Line a baking sheet with baking paper. Melt the butter.
Arrange the chicken legs on the baking sheet and brush with the melted butter. Season with smoked paprika, garlic powder, salt, pepper, and chopped rosemary.
Bake the chicken legs in the oven for 20 minutes. Flip them and bake for another 10 minutes.
Remove from the oven and let rest for 5 minutes before serving.