Preheat the oven to 350°F and lightly grease an 8x8-inch square baking pan (or 9-inch) with nonstick spray. You can also line it with parchment paper with overhanging sides for easy removal.
In a large bowl cream the butter and sugar until light. Beat in the eggs and then stir in the mashed banana, cooking oil, maple syrup, and vanilla until combined.
In a separate bowl, whisk together the flour, baking powder, baking soda and salt. Then stir the dry ingredients into the banana mixture until just combined.
Transfer the batter to the prepared baking pan and smooth the top.
Bake for 30 to 35 minutes, or until a toothpick inserted into the middle comes out mostly clean. Let the snack cake cool completely before cutting into servings.