Preheat the oven to 180°C Fan. Line a 9x9-inch square tin with parchment paper.
In a stand mixer, blend sugar and butter until smooth. Add flour and mix until dough forms—crumbly but evenly spread.
Press firmly into the pan; bake for 20-25 minutes until pale brown.
Remove and set aside. In a saucepan, melt condensed milk, butter, sugar, and golden syrup. Stir often to prevent burning.
Once sugar melts, increase heat; boil for 5-7 minutes, stirring constantly. Be cautious; it's hot and can splatter.
It's ready when it turns a slightly darker golden colour, resembling soft fudge.
Pour caramel over shortbread; refrigerate for an hour.
After setting, melt and pour milk chocolate, repeat with white chocolate.
Use a cake skewer to create a pattern in the milk chocolate.
Refrigerate for 1–2 hours until chocolate hardens.
Cut into pieces and savour your delicious cookies!