Whip the cream and sugar together until stiff. In another bowl, gently and carefully stir the lemon juice into the mascarpone. Fold the whipped cream into the mascarpone mixture. Fold gently so that the cream remains firm. Spoon the mixture into a piping bag, then place it in the refrigerator.

Prepare four small plates, gather the ladyfingers, and measure out the orange juice. Dip half of the ladyfingers in the orange juice and place three on each plate. Cut off the tip of the piping bag and pipe a layer of cream onto the ladyfingers.

Cut about half of the blackberries in half with a knife and spread them over the cream, pressing them in very slightly. Dip the remaining ladyfingers in the juice and place them on top of the filling.

Add another layer of cream, then finish with three whole blackberries on top.