Preheat the oven to 350ºF and line a 9×9-inch pan with parchment paper.
In a bowl, whisk together all the dry ingredients and set aside.
In a large mixing bowl, combine the mashed banana, pumpkin, and eggs until well combined. Add the vanilla, almond milk, and maple syrup, and mix thoroughly.
Gradually add the dry ingredients to the wet ingredients, mixing well. Then, add the melted coconut oil and mix until you have a thick batter.
Transfer the batter to the lined pan.
In a small bowl, mix the pumpkin and brown sugar. Dollop this mixture onto the batter and swirl it gently with a knife or toothpick. Sprinkle more chocolate chips on top.
Bake for 20 minutes, then rotate the pan 180º and bake for an additional 20 minutes.
Remove from the oven when a toothpick inserted mostly comes out clean. The cake will continue to cook for a few minutes.
Let the cake cool on a rack for at least 15 minutes before slicing.