Preheat oven to fan-assisted 160C / 180C /350F / gas 4 and lightly oil a 23 X 23 cm (9 inch by 9 inch) baking tray. (Silicon is good for this.)
Mash the bananas in a large bowl using a fork.
Then add in the sugar, oil, almond milk, 1 tbsp peanut butter and vanilla extract and mix until combined.
Then mix in the flour, cocoa powder, chocolate chips and salt until combined.
Pour the brownie batter into prepared baking tray, then add the peanut butter on the top and swirl into patterns.
Bake for approximately 27-30 minutes, until brownie starts shrinking away from the sides of the tin, the centre feels a bit springy and a skewer inserted comes out cleanly. (Careful not to overcook – the brownies will firm up as they cool down).
Allow the brownies to cool completely before cutting and serving.