Preheat the oven to 375°F/190°C and line an extra-large baking sheet with parchment paper.
In a large mixing bowl, mash the banana, we’ll want around 3/4 to 1 cup mashed. Add the remaining wet ingredients (eggs, oil, syrup or honey, vanilla and grated carrots) and whisk, until well combined.
In a large mixing bowl, whisk together the dry ingredients (oat flour, whole wheat flour, coconut, chia seeds, baking powder, cinnamon, baking soda, salt and ginger). Pour the wet ingredients onto the dry and stir until just combined, Add the chopped nuts and raisins, if using,
Scoop a scant 1/3 cup cookie dough onto the baking sheet. Continue, spacing an inch or so apart, for the remaining dough.
Bake for 16 to 18 minutes, until lightly firm to the touch with light golden bottoms. Once baked, allow to cool completely before glazing.
While the cookies bake, make the glaze, if using: To a small bowl, add the powdered sugar and stir in 2 teaspoons of milk, until smooth. We are looking for a spreadable consistency, not runny. If needed, add a little more milk, just 1/2 teaspoon at a time, and stir until smooth. Spread or pipe (I just add it to a baggie and snip a tiny piece off one corner) over the fully cooled cookies.