Preheat oven to 350 degrees Fahrenheit.
Line muffin tray with muffin cups or grease well and set aside.
In a medium size bowl whisk together all the dry ingredients and set aside.
1½ cups all purpose flour, 1 tsp baking powder, 1 tsp baking soda, 1 tsp cinnamon, ½ tsp ground ginger, ½ tsp salt, ¼ tsp nutmeg
In the bowl of your stand mixer beat together the egg with the sugars for 5 minutes at medium speed. Then, add in the oil and beat for another 2 - 3 minutes.
½ cup sugar, ¼ cup brown sugar, 1 egg, ⅓ cup vegetable oil
With the mixer speed set to low, slowly add in the dry ingredients and mix until just combined. Use a rubber spatula to scrape down the sides and then add in the mashed bananas. Mix until well combined. Add in the chopped walnuts and mix again until just combined.
3 bananas, 1 cup chopped walnuts
Divide the muffin batter evenly among the 12 muffin cups and bake in the middle rack of your oven for 25 - 30 minutes, or until done (a toothpick inserted into the center should come out clean).
Cool on a baking rack and enjoy!
Muffins will keep at room temperature, covered, for a few days and up to a week in the refrigerator. Wrapped well, they can also be frozen.