Preheat oven to 350 degrees. Line pans with cupcake liners (makes about 30 cupcakes). Place a Golden Oreo in the bottom of each liner.
Place bananas in a large bowl. Mash with a potato masher until completely smushed. Add cake mix, oil, eggs, and water. Mix for 30 seconds on low speed with a hand mixer, then 2 minutes on medium.
Scoop into prepared pans, filling about 3/4 full. Bake for 14-15 minutes, until a toothpick comes out clean. Cool completely before frosting.
To make frosting: beat cream cheese and butter until smooth. Slowly add powdered sugar and mix, 1 cup at a time, until combined. Add vanilla and beat until smooth. If needed to reach piping consistency, add a tablespoon of heavy cream (or 2). I didn't need to use any cream. Frost or pipe onto cupcakes (I used a 1M tip) and top with a 1/2 or full Golden Oreo.
Store in refrigerator.