Preheat your oven to 350°F (175°C). Prepare a 9×13-inch baking pan by greasing and flouring it or lining it with parchment paper.

In a mixing bowl, whisk together flour, baking soda, baking powder, salt, cinnamon, and nutmeg.

In another bowl, mix granulated sugar, brown sugar, and vegetable oil until smooth. Beat in eggs one at a time, followed by vanilla extract.

Fold in the mashed bananas until well combined.

Gradually stir in the dry ingredients until just combined, being careful not to overmix.

Gently fold in the grated zucchini until evenly distributed.

Pour the batter into the prepared pan. Bake for 50-60 minutes or until a toothpick comes out clean.

Cool the cake for about 1 hour in the pan, then transfer to a wire rack to cool completely.

Beat the cream cheese and butter until smooth. Gradually add powdered sugar and maple syrup until fluffy.

Frost the cooled cake with the maple frosting and cut into squares to serve.