Method

​1 Preheat the oven to 180°C/fan 160°C/gas mark 4 and line a couple of baking trays with baking parchment paper.

2 Put the butter and the sugar in a large bowl. Using an electric hand whisk, cream together until pale and fluffy. Add the egg and vanilla and mix well. Stir in the gluten-free flour, baking powder and bicarbonate of soda. Gently stir in the peanut butter and use your hand to bring it together into a ball of dough.

3 Divide the dough into 12 equal pieces and, using your hands, roll each one into a ball. Place on a large baking tray, spaced a good distance apart (try to have 10cm between them).

4 Flatten each one slightly with a fork, sprinkle over the toasted peanuts, if you're using them. Bake in the oven for 12-15 minutes, or until the cookies start to go golden brown. The cookies will still be soft when they come out of the oven but will firm up as they cool.

5 Remove from the oven and leave to cool on the baking tray. Enjoy!