If you only have yellow cake mix, (like I did), just spice it up. A mix of nutmeg, cinnamon, cloves, ginger and/or pumpkin pie spice will do the trick and THAT IS IT!!!!
If you want to up the yumminess factor, than go cray-cray with some add ins. My weapons of choice: Chocolate chips and blackberries. (Cranberries, walnuts, raisins, strawberries, mint or white chocolate chips, anything would be good). I mix in about 3 cups of chips, then after the mix is in the muffin tins, I cut the blackberries in half and dot them on the tops of the muffins. Then, bake at 350 degrees till toothpick inserted in center comes out clean and the muffins pull away from the sides. Easy, peasy and soOooOOoooOoooo delicious.