In a large mixing bowl, thoroughly mash the overripe bananas until mostly smooth (small chunks are fine for texture).
Add the melted coconut oil, granulated sugar, brown sugar, maple syrup, plant-based milk, and vanilla extract to the mashed bananas. Whisk until thoroughly combined.
In a separate bowl, whisk together the flour, baking soda, baking powder, salt, cinnamon, cardamom, and orange zest.
Add the dry ingredients to the wet ingredients in two additions, folding gently with a flexible spatula just until no dry flour remains visible. Do not overmix—a few small lumps are preferable to overmixing.
Gently fold in the toasted walnuts and/or chocolate chunks with just a few strokes to distribute evenly.