Preheat the oven to 350 degrees F (175 degrees C). Generously grease a 10-inch fluted tube pan (such as Bundt®).

Whisk flour, cinnamon, baking powder, baking soda, ginger, salt, nutmeg, cloves, and allspice together in a medium bowl.

Whisk bananas, pumpkin, yogurt, maple syrup, eggs, and vanilla extract together in a large bowl until thoroughly combined and no lumps remain. Pour in half of the dry ingredients and mix until just combined. Add in remaining dry ingredients and mix until just combined. Fold in chocolate chips and walnuts. Pour batter into the prepared pan.

Bake in the preheated oven until a toothpick or bamboo skewer inserted into the center of the cake comes out clean, 50 to 55 minutes. Allow cake to cool in the pan for 10 to 15 minutes. Gently run a knife around the edges of the cake to loosen. Invert onto a wire rack and allow to cool completely.