In a large bowl stir together cake mix and pumpkin puree.
Fold in the chopped walnuts.
Line a muffin pan with cupcake liners or spray generously with cooking spray. Fill liners 2/3 full with batter.
If desired, sprinkle with raw sugar.
Bake at 350 degrees for 30-35 minutes. Be sure to test for doneness with a toothpick. Baked goods with pumpkin are notorious for staying raw in the middle.