Preheat the oven to 180ºC Line two 12-cup muffin tins with paper liners. In a large bowl, mix together the flour, sugar, baking powder and salt. Set aside. In another large bowl, mix together the banana, canola oil and eggs. Gradually add dry ingredients to banana mixture, alternating with the milk, adding dry ingredients last. Stir in the nuts. Measure out batter evenly into lined muffin cups, filling 0.875 full. Bake 25 minutes, until muffins are puffed and golden brown.