Preheat the oven to 350°F. Line a baking sheet with parchment paper and set aside.
In the bowl of a stand mixer, mash the bananas. Mix in the oil and egg until fully incorporated.
Add in 1 cup of the graham cracker crumbs and the cake mix. Mix until fully combined.
Using a medium cookie scoop, scoop the batter onto the prepared baking sheet. Sprinkle the tops with the remaining graham cracker crumbs.
Bake in the preheated oven for 8-10 minutes. Allow to cool on the pan for around 3 minutes, then transfer to wire racks to cool completely.