Preheat your oven to 180°C (160°C Fan, gas mark 4) and line a baking tray with parchment paper.
With a grater, zest one lemon and harvest the zested peel into a small bowl. Then cut the lemon in half and juice each piece with a juicer or squeeze by hand.
Cream butter, sugar, lemon zest and lemon juice together until light and fluffy. You can do this with a food processor, electric whisk or by hand with a wooden spoon.
Add plain flour to the mixing bowl and mix together until a dough has formed. Use your hands to gather the dough together to form a ball.
Lightly flour your work surface and place the dough on top of it.
With a lightly floured rolling pin, roll the dough out until it has a 1cm (half an inch) thickness. Use a cookie cutter to cut-out circles. I used a 6cm fluted cookie cutter.
Place the cut-out dough onto a lined baking tray and bake in the oven for 10 minutes or until baked through. Leave the biscuits to cool down before eating.