Preheat oven to 350 degrees.  Prepare mini muffin pan by spraying each cup liberally with non-stick cooking spray.  Place a mini Vanilla Wafer into the bottom of each muffin cup. Pour yellow cake mix into a medium bowl and whisk {or sift} to remove any lumps.  Add softened butter and eggs to the cake mix and combine with a hand held mixer until dough is thick and sticky.  Using a small cookie scoop {or 1/2 tbsp.}, put a mound of cookie dough into each muffin cup on top of the vanilla wafer.  Using your fingers, go back and press the mound of dough down to create a level cookie.  Bake for 9-11 minutes.  {Do not over cook, they will set up as they cool.}  Remove from oven and immediately run a knife around the edge of each cookie cup {I used an offset butter knife}.  Go back and use a tart shaper {or end of a wooden spoon} to press middle of cookie down and create a indentation.  Move cookies to cooling rack and let them cool completely. Continue to bake second batch if necessary.

While the cookies are cooling, combine the instant vanilla pudding mix and milk with a whisk {or hand held mixer}. Once that is combined and thick, add the whipped topping and fold it into the vanilla pudding mixture. Finally, fold in the chopped banana chips.

Take a heaping teaspoon of filling and place into the indentation of each cookie cup. Top with a dollop of whipped topping and a banana chip if desired. Store in an air tight container in the refrigerator for up to 4 days.