Prep: 10 minutes; Cook: 25 minutes.
Preheat oven to 350°. Combine first 6 ingredients (through sugar) in a bowl. Whisk together oil, soy milk, and vanilla in a separate bowl. Add wet mixture to dry ingredients; stir to combine. Fold in banana, walnuts, and chocolate chips.
Line a baking sheet with parchment paper. Scoop dough onto pan with a small ice-cream scoop. Bake 25 minutes or until golden brown, turning baking sheet halfway through. Let cool on a wire rack.