Cut the mango cheeks from the stones. Using a large spoon, remove the mango fruit from the cheeks and thinly slice the fruit crossways.
Whip the cream to soft peaks in a chilled bowl. Add the icing sugar and mascarpone. Use a balloon whisk to gently stir until the cream is thick.
Carefully cut the lamington fingers in half. Spoon or pipe the mascarpone cream onto one lamington half. Top with sliced mango and sandwich with lamington top. Top with a little cream and another slice of mango. Chill and serve.
TipThe lamington fingers can be made up to 6 hours before serving.