Preheat oven to 240°C.
Sift the flour, baking powder and salt together.
Add the butter and rub into flour with fingers very lightly.
Beat the egg, maas and water together.
Add to dry ingredients and mix into a medium to firm dough.
Turn onto a lightly floured surface and pat out to 3 cm thick.
Cut into rounds with a 5 cm cutter.
Place on a lightly greased baking tray and bake for 12 - 15 minutes.