Preheat oven to 350 degrees F (175 degrees C). Lightly grease the loaf pan. Or use the parchment paper to cover the bottom of the pan.
In a large bowl, combine flour, baking soda & salt. In a separate bowl, mix the butter and brown sugar together. Stir in eggs, mashed bananas and mandarin cubes until well blended. Stir banana mandarin mixture into flour mixture; stir just to moisten then fold them by a spatula to make sure the flour is mixed well.
Bake in preheated oven for 50-60 minutes. Test the bread using a toothpick inserted into center of the loaf. It’s done if the toothpick comes out clean. Let the bread cool in pan for 10 minutes then bring the bread to a cooling rack.