Grease a 3cm deep, 16cm x 26c m slice pan. Line base with baking paper. Allow a 2 cm over hang on all sides.
Place half of condensed milk, sugar, glucose syrup, golden syrup and butter in a heavy based sauce pan over low heat. Cook stirring with out boiling for 5 minutes or until sugar has dissolved.Increase heat med-low . Bring to a simmer, stirring. Cook, stirring for 4-5 minutes or until mixture thickens. Remove from heat. Stir in half the chocolate until melted and well combined. Working quickly , spoon into pan and spread evenly. Smooth top. Set aside for 20 minutes.
Meanwhile lightly dust a flat surface with icing sugar. Knead icing until smooth. Continue kneading , gradually adding vanilla in 2 batches. (add more icing sugar if necessary). Roll icing out between 2 sheets of baking paper to form a 5mm thick 20cm x 30cm. Cut a 17cm x 27cm rectangle from icing. Carefully place icing on caramel mixture. Press lightly to secure.
Repeat step 2, spooning mixture on top of icing. Smooth . Set aside for 20 minutes.
Cover pan with plastic wrap. Refrigerate overnight or until firm.Remove from pan. Trim all sides.Cut into 2cm pieces. Serve.