Preheat oven to 350. Prepare 24 muffin cups with parchment liners or grease and flour.
Combine milk and oats; set aside.
Combine cake mix, butter, eggs, and cinnamon. Stir as well as possible. Beat in oat mixture. Fold in raisins. Spoon into prepared cups.
Bake 14 minutes. Remove from pans to cool.