For the mascarpone cream, beat the egg yolks with the sugar until you get a fluffy mixture. If you have any doubts about the origin of the eggs, you can do this in a container in a water bath, but be careful not to cook the eggs and ruin their smooth texture.
Separately, beat the egg whites into hard snow and carefully mix them with the yolks. Stir slowly and add the mascarpone in portions. Finally, add marsala or rum and put it in the refrigerator while you make the eclairs. Put the water and oil to boil on the stove and then add the flour.
Stir for a few minutes until the mixture thickens and comes off the walls and bottom. Remove from the heat and let it cool. Once the mixture cools, add the eggs one at a time and mix well after putting in each one. Make a thick and sticky dough.
With a spoon, scoop up some dough and drop it gently onto a large tray with baking paper. There needs to be space between the éclairs. You can use an icing piping syringe to spray on the mixture.
Put the éclairs to bake in a preheated 392°F (200 °C) oven for about 30 minutes. Then leave them to cool completely in the oven, with the door slightly open. Fill the cooled eclairs with the mascarpone cream.