Preheat oven to 400° F. Lightly grease a muffin pan with nonstick cooking spray or butter.
In a small bowl, combine cranberries and sugar. Set aside.
Prepare cornbread batter per package instructions. Spoon batter into prepared pan, filling each cavity 2/3 full.
Sprinkle 5-7 cranberries on top of each muffin. Bake for 11-14 minutes, or until a toothpick inserted into the center comes out clean.