Mash up bananas with mixer until pulped well, Add the gelatin, You could also use a food processor or blender to do the entire mixing of this cake.
To the above mixture, add the ingredients from the box of cake mix. Mix well. Add the cake mix, mix well.
Pour into the prepared bundt pan and bake until a knife or skewer comes out clean.
Remove from oven and let cool on wire rack [do not turn out cake yet].
When cool,turn out the cake on a plate or platter and let it finish cooling before cutting.
I do not ice this cake, but a little cream cheese icing would work well. Also while cooling, you can poke some holes with the skewer and pour light rum into the cake if you're so inclined.