Place the pistachios in a food processor or blender. Process until the mixture resembles coarse breadcrumbs. Alternately place the pistachios into a plastic bag and beat with a rolling pin until the mixture resembles coarse breadcrumbs. Set aside.
Use an electric mixer to beat the butter, castor sugar and a pinch of salt in a medium-sized mixing bowl until creamy. Add the egg, lemon zest and lemon extract until combined. Stir the flour, 60g of the pistachios and baking powder into the mixture, tablespoon by tablespoon until just combined. As the dough forms, you will need to use your hands. Transfer dough to a clean work bench and knead until smooth.
Note: 00 is a powder-fine Italian type of flour. It is made from soft wheat varieties, and is frequently used in Italian desserts and pastas. 00 flour is available in most supermarkets, Italian food stores and gourmet delicatessens.
Line 2 shallow baking trays with baking paper. Preheat the oven to 180°C conventional oven (350° Fahrenheit/Gas 4). Adjust the metal racks to the middle groove of the oven.
Roll 1 tablespoonful of the dough into a ball, then place it on the prepared baking tray. Repeat using the remaining cookie dough, ensuring that the balls of dough are well spaced out to allow room for spreading. Use your finger to lightly press in the centre of each ball to slightly flatten. Sprinkle the cookies using the remaining 15g of pistachios. Cover the trays with Italian pistachio lemon cookies with cling film (plastic wrap) and refrigerate for a minimum of 30 minutes.
Bake one tray at a time on the middle groove of the oven for 13-15 minutes or until just golden. Transfer to a wire rack to cool completely – buon appetito!
Tip: Once cooled, store cookies in an airtight container.