Step 1

Cream the butter with the sugar in a free-standing mixer until pale and light – this will take about 3 minutes. Scrape down the insides of the bowl from time to time to ensure that all of the ingredients are thoroughly incorporated. (Alternatively use a hand mixer and a large bowl.)

Step 2

Add the egg and beat until thoroughly incorporated. Sift the flour, bicarbonate of soda, cinnamon and salt into the bowl and mix until barely combined. Add the pecans (or walnuts), chocolate chips and mashed banana and mix again until all of the ingredients are thoroughly incorporated. Cover the bowl and chill for 1 hour (see Recipe Tips).

Step 3

Preheat the oven to 180C/160C Fan/Gas 4 and line 2 baking sheets with baking paper.

Step 4

Shape level tablespoons of dough into balls and place on the prepared baking sheets leaving plenty of space between each one to allow for spreading during cooking. Slightly flatten each cookie with your hands and bake in batches on the middle shelf of the preheated oven for 11–12 minutes until crisp on top and golden brown. The cookies will still be slightly soft but will crisp further on cooling.

Step 5

Remove from the oven and leave on the baking sheets. These cookies will be slightly soft due to the banana and should be stored in an airtight container.