Preheat the oven to 170 degrees Celsius (340 degrees Fahrenheit)
Combine all the ingredients in a large bowl (no need to sift the flour) until you get an easily moldable but firm dough – add more milk if necessary to achieve the right consistency
Sprinkle some flour on a clean surface or chopping board, and use a rolling pin to roll the dough until it’s around 1cm thick
Use a cookie cutter to cut the shortbread to whatever shape you like
Alternatively, you could just roll the dough into a log shape, then slice them into 1cm-thick rounds
Arrange them on a greased baking tray
Bake in oven for around 25 minutes, until they’re firm to the touch (don’t worry if they’re not completly hard though, they tend to firm up when cooling)