- 
          
          Beat together the margarine and brown 
          sugar in a bowl until light and fluffy. Beat in the flour and rolled 
          oats. Use your fingertips to bring the mixture together if necessary.
             
            - 
          
          Press the mixture into the base of a 
          shallow 20cm square cake tin.
             
            - 
          
          Bake in a preheated oven at 180 degrees 
          Celsius for 25 minutes or until just golden and firm. Cool in the tin.
             
            - 
          
          Place the ingredients for the caramel 
          filling in a pan and heat gently. Stir until the sugar has dissolved 
          and the ingredients combined. Bring to the boil over a very low heat, 
          then boil gently for 3-4 minutes, stirring constantly until thickened.
             
            - 
          
          Pour the caramel filling over the 
          biscuit base in the tin and leave to set.
             
            - 
          
          For the topping, melt the dark chocolate 
          and spread over the caramel. Melt the white chocolate and pipe lines 
          of white chocolate over the dark chocolate. Using a cocktail stick or 
          a skewer, feather the white chocolate into the dark chocolate. Leave 
          to set.
             
            - 
          
          Cut into squares and serve.