Preheat oven to 180 deg C.Line a square baking tray with parchment paper.Set aside until required.TO PREPARE THE BASEIn a large mixing bowl,beat together butter and sugar until light and fluffy.
Add the all purpose flour and oats.Mix gently using your finger tips until well combined.
Transfer this mixture into the prepared baking tin and press to form an even layer.
Bake in the preheated oven for about 25 minutes or until golden brown and firm.Allow to cool completely.TO PREPARE THE CARAMEL FILLINGIn a sauce pan ,add all the ingredients listed under 'For caramel filling'.Cook stirring constantly until the mixture starts to boil over low flame.Cook for about 3 to 4 minutes stirring continuously until the mixture has thickened.
Pour this caramel filling over the prepared base and level the top using a spoon or a palette knife.Aloow to cool completely.
TO PREPARE THE CHOCOLATE LAYERMelt the plain chocolate using a double boiler.
Spread the melted chocolate over the caramel layer.Allow to set completely, cut into squares and serve.