Mash the bananas with a potato masher and set aside.
Add the softened butter to the sugar and use a spatula to cream together until light and fluffy.
Add the remaining dry ingredients in a different bowl and whisk together to remove lumps.
Add the mashed bananas to the sugar and butter, whisking to incorporate. Add the eggs, milk and vanilla and mix until it forms a smooth batter. Add the chocolate chips and mix in.
Add the flour and use a spatula to mix the batter just until no visible flour remains.
Bake at 160°C for an 1 hour - 1 hour and 10 minutes, until a skewer comes out clean.