Preheat oven to 350°F. Line an 8-inch square baking pan with parchment paper or greased foil. Set aside.
In a large bowl, add peeled banana. Using a fork or dough blender (recommended), mash until smooth. Add the remaining wet ingredients: peanut butter, maple syrup, coconut oil, flax egg and vanilla. Whisk until well incorporated.
Add the dry ingredients: oats, baking soda, baking powder and salt. Using a rubber spatula, fold until well mixed. Fold in seeds, dried fruit and walnuts.
Pour this mixture into the prepared baking pan. Using the rubber spatula, smooth into an even layer.
Bake for 12-18 minutes, until just lightly golden around the edges. Mine took 15 minutes. Cool for about 1 hour. Slice into bars. Enjoy! Storing instructions below.