In a stand mixer with paddle attachment, beat the butter and caster sugar on medium speed until light and fluffy (2 minutes)
Add egg and vanilla and beat again.
In a separate bowl, combine the dry ingredients.
Gradually add combined dry ingredients, while mixing on low until a soft dough just forms.
Halve the dough, then then press each half into a disc. Wrap each disc tightly in plastic wrap and refrigerate for 2-3 hours, or even overnight.
Preheat oven to 180℃/350℉ and line 2 baking trays with baking paper or silpat mats.
Roll the chilled dough between 2 sheets of baking paper to 3-4mm thick. Do one disc of dough at a time, then freeze the rolled out dough for 5 minutes (no longer). This will make the cut out shapes easier to handle.
Cut shapes (hearts, scalloped circles, daisy etc.) from the dough and place onto the lined baking sheets, using an offset spatula to lift the shapes.
Once on the baking sheets, use a small cutter to cut a centre hole in half of the cookies. Remove the hole (or bake for mini cookies)
Bake cookies for 10-12 minutes, turning after 8 minutes, if necessary, until the cookie tops look dry and very lightly golden.
Cool on tray for 5 minutes, before cooling completely on a wire rack.