In a small saucepan, heat the cream, then add the grated Grana Padano PDO. Mix well, add a pinch of pepper and the finely chopped chives and marjoram. Set aside and allow to cool off.
In the meantime, use star shaped pastry cutters to cut out different size stars from the slices of bread. For each tree you will need a large star at the base, a medium star in the middle, and two small stars on top.
Spread a layer of Grana Padano PDO cream on the large star at the base, put some sun-dried tomato on top and add a bit of lemon zest.
Proceed in the same way with the other stars, till you reach the top layer. Position the last small star vertically. As a finishing touch, dust with grated Grana Padano PDO.