Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish.
Combine flour, maple syrup, cocoa powder, baking powder, and salt in a large bowl; blend well and make a well in the center. Combine mashed bananas, coconut milk, olive oil, and vanilla extract in a second bowl. Pour banana mixture into the flour mixture and stir until batter is evenly mixed. Fold in chocolate chips. Pour batter into the prepared baking dish and sprinkle with cocoa nibs.
Bake in the preheated oven until a toothpick inserted in the center comes out clean, about 30 minutes. Let cool completely before slicing.