Preheat oven to 450F. Set aside roasting pan fitted with rack.
Pat chicken dry inside and out. Sprinkle outside evenly with salt and jalapeño. Pat spices down to ensure they stick to skin.
Place chicken on roasting rack and transfer to oven. Roast for 45 minutes.
Brush butter onto chicken and roast an additional 15 minutes, until chicken is golden and cooked through.
Allow chicken to rest 10-15 minutes before serving.