01 -
Preheat oven to 350°F (175°C). Grease two 4x8-inch loaf pans.
02 -
Combine flour, baking soda, baking powder, cinnamon, and salt together in a bowl.
03 -
Beat brown sugar and butter together in a separate bowl using an electric mixer until smooth and creamy.
04 -
Stir flour mixture, alternating with mashed bananas, into creamed butter mixture just until batter is mixed; fold in carrots and walnuts.
05 -
Pour batter into the prepared loaf pans. Bake in the preheated oven until a toothpick inserted in the center of a loaf comes out clean, 50 to 60 minutes.