450g butter, softened
1/2 cup caster sugar
1 1/2 tsp vanilla extract
3 cups plain flour
1 x 380g can Top'n'Fill, stirred until smooth
3/4 cup thickened cream
3 Tbsp glucose syrup
340g dark cooking chocolate
To make crust, put 330g of the butter in the large bowl of an electric mixer and beat on medium to high speed for 30 seconds. Add sugar and vanilla. Continue beating until combined, scraping sides of bowl occasionally. Beat in as much of the flour as you can with the mixer. Using a wooden spoon, stir in any remaining flour. Cover and chill for 30-60 minutes or until dough is easy to handle.
Preheat over to 180C. Line a 30 x 20 x 5cm slice tin with baking paper. Press dough evenly into bottom of prepared tin. Chill 20 minutes. Bake 20-25 minutes or until top is light brown. Cool in tin on wire rack. Spread Top'n'Fill evenly over crust.
Put cream, remaining butter and syrup in a medium saucepan over medium heat and bring to just boiling. Remove from heat. Add chocolate (do not stir). Let stand for 5 minutes. Stir until smooth. Cool 10 minutes. Pour chocolate mixture over caramel layer evenly. Cover and chill 1-2 hours until mixture is set. Using edges of baking paper, lift out of tin. Cut in squares and serve.