In a stand mixer or bowl, cream butter and shortening until softened; add sugar and beat until well combined. Add the bananas (mash beforehand if mixing by hand). Beat in the eggs and vanilla.
Combine the dry ingredients (up to the coconut) and add to the wet mixture. Mix just until combined. Add in the coconut and butterscotch chips.
Pour mixture into prepared pan. Bake for 50–55 minutes, until a toothpick inserted in the middle comes out clean.