Cream butter and sugar with an electric mixer until light and fluffy. Add egg and vanilla and beat until combined. Add baking powder and flour and use a wooden spoon to beat until combined. Divide mixture into 3 equal-sized balls.

Press each piece of dough (green, red and uncoloured) into a flat square and wrap in plastic wrap. Refrigerate the dough for 1 hour or until firm.

Remove the dough squares from the fridge. Place the red dough between 2 sheets of parchment paper or waxed paper. Use a rolling pin to roll out the dough to a 25cm square. Leave dough between parchment.

Repeat with the other 2 pieces of dough. Refrigerate cookie dough for 30 minutes.

Remove dough from the fridge, and take the top layer of parchment off each sheet of cookie dough. Place the red dough down on a counter. Top with the white dough, non-parchment sides touching. Be sure to try and line up the edges of the dough as much as possible.

Remove the parchment from the white dough. Top the white with the green, non-parchment sides touching, being sure to line up the edges. Remove parchment from the green dough. Use a pizza cutter to trim the left and right edges of the cookie dough into straight lines.

Very carefully, starting with one of the straightened sides, roll the dough into a long shape until you reach the other trimmed dough edge. Use the parchment paper to lift the dough to get it started. Once the dough log is complete, gently pinch the seam closed along with any breaks on the outer red layer.

Wrap the dough log in plastic wrap and refrigerate for 1 hour or until firm.

Preheat oven to 180°C and line 3 x baking trays with baking paper.

Use a sharp knife to cut the dough log into 5cm-thick slices. Place the cookies on your prepared baking sheets and bake for 12 to 15 minutes, or until the cookies are just starting to turn golden.

Remove from oven and cool on baking tray for 5 minutes before transferring to a wire rack to cool completely. Serve immediately or store in an airtight container until ready to serve.