Shortbread can be made up to two weeks ahead. Store in an airtight container at room temperature. Sprinkles are available from Spotlight stores and cake decorating shops. Divide shortbread among cellophane bags to give as gifts.
250g unsalted butter, chopped, at room temperature
1⁄2 cup caster sugar
1 3⁄4 cups plain flour
1⁄2 cup rice flour
1⁄4 cup red and greensprinkles
Grease an 18cm x 28cm rectangular slice pan. Line base and sides with baking paper, extending paper 3cm above pan edges.
2. Beat butter and sugar in a large bowl of an electric mixer until light and fluffy. Add flours. Stir to form a soft dough. Press into prepared pan. Smooth over top. Scatter over sprinkles. Press into dough and then freeze until firm.
3. Line two oven trays with baking paper. Lift the dough out of pan. Cut into 2cm squares. Arrange squares 2cm apart on prepared trays.
4. Cook in a moderately slow oven (160C) for about 20 to 25 minutes, or until lightly browned and rm to touch. Cool on trays.