Preheat the oven to 200C (fan). Combine the flour, sugar, cream of tartar and bicarbonate of soda (or baking powder), then add the butter and rub well until the mixture resembles fine breadcrumbs
Add the lemon, vanilla (if using) and slowly add the milk while stirring. As you stir a soft, sticky dough will form. You may not need to use all the milk
Put the dough on a floured work surface and fold and pat a few times until smooth, being careful not to overwork the dough. Roll the dough out until ½ inch (1cm) thick, then fold over and pat lightly. Cut out round with a lightly floured cookie cutter that is about 7cm (3 inches) across.
Place the rounds onto a lined baking sheet, then brush the tops with egg
Bake for 10 minutes, until golden brown and risen
Enjoy!
