Preheat oven to 350F. Line two medium sheet pans with parchment paper and set aside.
In a large bowl, mix sugars with melted butter, mashed banana, egg, and vanilla until smooth. Fold in flour, oats, baking soda, cinnamon, and salt until dough is just combined.
Fold shredded zucchini, walnuts, and chocolate chunks into dough until just combined (dough will be slightly sticky)
Scoop dough into 1 inch balls and space 2 inches apart on sheet pans. Flatten dough balls slightly.
Bake cookies at 350F 11-13 minutes until cookies are golden brown around the edges. Allow cookies to cool on sheet pan 10 minutes, then transfer to a wire cooling rack. Enjoy cookies warm!