Grease a 19 cm x 30 cm lamington pan. Line base and sides with baking paper.
Place butter and chocolate in a medium heatproof bowl. Sit bowl over a pan of simmering water. Stir until smooth. Remove. Using a wooden spoon, stir in sugar and eggs. Add 1 cup of the flour. Mix well. Pour mixture into prepared pan. Smooth top.
Place Caramel Top’n’Fill and remaining flour in a medium bowl. Stir to combine. Place tablespoonfuls of mix over brownie mixture. Using end of a spoon, swirl to give a marbled effect. Tap pan on bench to flatten mixture.
Cook in a moderate oven (180C) for about 30 minutes, or until cooked when tested. Transfer to a wire rack. Cool in pan.
Remove from pan. Cut into squares. Serve with cream. Decorate with shaved chocolate.