In a food processor add the peeled bananas and pumpkin puree. Blend until smooth.
Add in the baking soda and cocoa powder, blend together.
Add in the rest of the brownie ingredients and blend once again until smooth and well combined.
Pour the batter into a greased 8x8 baking dish and bake until set, 25-30 minutes.
At this point the brownies will still look raw in the center but they will set once cooled. I like to keep them in the fridge which will make them nice and fudgy.
Clean out the food processor to make the frosting.
Add all of the ingredients for the frosting to the food processor and blend until smooth and combined.
Spread the frosting evenly onto the cooled brownies.
Allow to set in the fridge and then cut in to 16 squares.
Store leftovers in the fridge for up to one week or in the freezer for up to 1 month.