Preheat Your Oven: Begin by preheating your oven to 350°F (175°C). Grease a sheet cake pan to prepare for your batter.
Combine Wet Ingredients: In a large mixing bowl, whisk together the sugar, eggs, and vegetable oil until smooth and creamy.
Add Bananas and Zucchini: Stir in the mashed bananas and grated zucchini; mix well to combine all the flavors.
Mix Dry Ingredients: In another bowl, whisk the all-purpose flour, baking soda, baking powder, salt, and cinnamon.
Combine Mixtures: Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix!
Pour into Pan: Pour the cake batter into your prepared sheet cake pan, smoothing it out evenly.
Bake: Place in the oven and bake for 25-30 minutes. To check if it's done, insert a toothpick in the center. If it comes out clean, it’s ready!
Cool and Serve: Once baked, allow the cake to cool for a few minutes in the pan before transferring it to a wire rack. Dust with powdered sugar or top with cream cheese frosting if desired!