This makes ~18 muffins
Preheat oven 350ºF. Line or grease a muffin tin. Makes 18-24 muffins, depending on how full you fill each cup. I baked mine at 400*
Mix cake mix, pumpkin, eggs, vanilla, and cinnamon. Blend with mixer on low 1 minute, scrape down. Or mix by hand.
Increase speed to medium 2 minutes. Scrape down. Batter will be thick.
Fold in chocolate chips. Spoon batter into muffin tin. Bake 20-25 minutes. (or 10-12 minutes at increased temperature.)