Preheat and prepare: Set your oven to 180°C (160°C fan) and line a large baking tray with parchment paper. The paper should lie flat and crisp; if it curls, fold the edges under themselves to keep it flat.

Mash the bananas: In your large mixing bowl, mash the bananas thoroughly with a fork until they form a smooth, almost liquid paste with no visible lumps. You should see a pale, creamy yellow purée with a sweet, floral banana aroma.

Add the wet ingredients: Pour in the melted butter, brown sugar, egg, and vanilla extract. Stir vigorously with your wooden spoon until the mixture looks glossy and evenly combined, about 20 to 30 seconds. The sugar should be mostly dissolved, and the batter will smell deeply of vanilla and caramel.

Combine the dry ingredients: Sprinkle the flour, oats, bicarbonate of soda, cinnamon, and salt over the wet mixture. Fold gently with your spoon until just combined — stop as soon as you no longer see streaks of white flour. The dough will look slightly sticky, thick, and speckled with oat flakes.

Fold in the chocolate: Tip in the chocolate chips and fold them through the dough with three or four turns of the spoon. You want the chips evenly distributed, with some peeking through the surface for visual appeal.

Scoop and shape: Using a cookie scoop or a tablespoon, drop rounded mounds of dough onto the prepared tray, spacing them about 5cm apart. Each mound should be roughly the size of a golf ball, with a slightly rough, craggy surface.

Bake until golden: Slide the tray into the middle rack and bake for 11 to 13 minutes. The cookies are done when the edges are set and lightly golden brown, while the centres still look slightly soft and puffy. You should smell warm bananas and toasted oats wafting from the oven.

Cool and set: Leave the cookies on the tray for exactly 5 minutes — they will continue to firm up as they cool. Transfer them to a wire cooling rack using a thin spatula. The finished cookies should feel soft when pressed gently but hold their shape without crumbling.