Line a 6-inch springform cake pan with parchment paper at the bottom and sides of the pan. Using a cooking spray, oil the sides and bottom. You must use a springform pan and line the pan properly for easy release of the cake.

Add the chocolate chips to a glass bowl. Place the glass bowl over a saucepan filled with boiled water (not over the stove; place it on a wooden board).

Stir the chocolate chips with a silicone spatula until all the chips are melted in a shiny liquid chocolate mixture. (Note 3 below for microwave).

In a large mixing bowl, mash the bananas as smoothly as possible using a fork or a potato masher. If there are lumps, it's okay, but you will see the banana lumps in the cake. For no lumps, blend the bananas in a blender.

Pack the mashed banana in a measuring cup to measure exactly 1 cup. Sweep off the excess and freeze it for later. Return the cup of mashed bananas to the mixing bowl.

Pour the melted chocolate over the mashed banana and stir to combine. You can also blend both ingredients to completely remove any lumps of banana.

Pour the batter into the prepared pan.

Refrigerate for one hour or overnight, or simply until firm and the top is hard if you press on it.

Open the springform sides, peel off the parchment paper on the sides, and keep the cake on the pan base. If you like, drizzle the top of the cake with vegan ganache on top or simply some shredded chocolate to decorate.