Mix the linseed with the water in a glass and set aside.

Cream the butter with the sugar until well combined.

Dry fry the pistachios until they just start to release a nutty smell (2-3 minutes). Remove from the heat and tip onto a cool plate. Roughly chop.

Add vanilla to the linseed mix, then stir into the creamed mixture.

Put the flour in the bowl, along with the bicarbonate of soda, baking powder and salt. Mix until combined.

Reserve a handful of pistachios, then mix the rest into the dough along with the chocolate. Make a ball with the dough (I put mine in a clean bowl), cover and refrigerate for 20-30 minutes.

Prepare a baking tray with a non stick liner or baking paper. Pinch off golf ball sized bits of dough (or use a cookie/ice-cream scoop) and space out on your tray. You should get 15 balls. Slightly press each ball down to flatten slightly, then sprinkle with the remaining pistachios.

Bake at Gas Mark 4 (350f / 180c) for 12-15 minutes. The edges will be golden and the cookies will have spread slightly. Allow to cool on the tray for a few minutes before removing on to a wire rack to cool completely.

Enjoy!