Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan and set aside.
In a large mixing bowl, combine the mashed bananas, granulated sugar, brown sugar, vegetable oil, eggs, and vanilla extract. Mix until well combined.
In a separate bowl, whisk together the flour, baking soda, baking powder, cinnamon, and salt. Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Fold in the grated carrots, walnuts, and raisins if using. Be careful not to overmix.
Pour the batter into the prepared loaf pan and smooth the top. Bake for 55-65 minutes, or until a toothpick inserted into the center comes out clean.
Allow the bread to cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely.
While the bread cools, prepare the frosting by beating the softened cream cheese and butter together until smooth. Add the vanilla extract and cinnamon, then gradually mix in the powdered sugar. If the frosting is too thick, add milk a tablespoon at a time until desired consistency is reached.
Once the bread is completely cool, spread the cinnamon cream cheese frosting on top. Slice and serve.