Mixing with cream cheese: Beat the mascarpone and sugar in a deep bowl until the mixture is fluffy. Continuing to stir, add the juice and rind of oranges and cornstarch / flour. Add the egg and beat briefly to mix all products. Making chocolate mixture: melting chocolate and the butter in a water bath or in the microwave on low power. Leave to cool. Beat eggs, sugar and vanilla. Add to chocolate mixture and put the flour and beat well. Turn oven to heat to 180C. Prepare a rectangular baking pan with long side 23 cm. Greased and pour the chocolate mixture. Top with a tablespoon of white mixture Give a great deal. With a metal spatula or spoon gently stir in a circular motion to get * * marble pattern. Bake the cake 30-35 minutes until slightly rise at the ends and tighten the middle. Cake is removed after completely cooled and cut into squares.