Preheat the grill or oven to 350F.
In a large bowl, whisk together the flour, cinnamon, ginger, nutmeg, cloves, baking soda, baking powder, and salt.
In a separate large bowl, whisk together the melted butter, brown sugar, granulated sugar, eggs, vanilla, mashed bananas, and pumpkin puree. There will be lumps from the banana.
Make a well in the middle of the dry ingredients and pour the wet ingredients into the well.
Gently fold the ingredients together.
If adding in chopped walnuts, add when toward the end of folding.
Spoon the batter into the prepared pan and smooth the top.
Top with chocolate chips if adding.
Bake in the preheated grill (or oven) for about 55-65 minutes, or until 200-205° IT.
I started to check around the 45-minute mark.
Cool in the pan for at least 20-25 minutes before carefully transferring to a wire rack to continue cooling.
