Preheat oven to 180C/160C fan/gas mark 4.

Sift the flour and baking powder together in a bowl.

In a different bowl beat the soft butter and sugar together before adding in the peanut butter and mixing well.

Add the egg and flour, mixing it in until it is well combined into a smooth dough.

With lightly floured hands, form small balls from the dough, about the sizes of walnuts, place them on a lined baking tray with space in between.

Using the back of a fork, press each dough ball down to flatten it. Create a cross by pressing it down again in the other direction. This helps to make sure the cookie cooks evenly throughout.

Place in the oven and bake for 8 to 10 minutes until golden brown. The cookies will be soft when you first take them out of the oven, but they will continue to cook and harden up as you leave them to cool down.

Once they have cooled down, transfer them to a plate for serving, or an airtight container for storing.

Optionally sprinkle with some icing sugar before serving.