First, separate the egg yolks from the egg whites into different mixing bowls. With an electric whisk, start whipping the egg yolks and pour in only half of the sugar (¼ cup). Keep whipping the yolks and sugar together until everything is frothy and well mixed.
Keep the whisk running while you add the mascarpone in, little by little, until all of the cheese is incorporated with the yolk mixture and it becomes a thick and compact cream. Set aside.
Clean off the whisk and move on to the egg whites. Again, start whipping the whites and slowly adding in the other half of the remaining sugar, a little at a time. Keep doing this until it becomes stiff and peaky.
Now, take a spoonful of the egg white mixture and add it to the yolk mixture – mix vigorously with a spatula. Proceed to add the rest of the egg whites in little by little and very gently mix them in from the bottom up.
Take a baking dish and line it with the ladyfingers then add the cold espresso and let them soak for a few minutes, flipping them halfway so both sides can soak.
Now, to actually make the cups you will first want to break a lady finger in half and line the bottom of the cup with it. Add a spoonful or two of the cream mixture, tap your cup down on the table so the layer settles, add another lady finger layer, and another cream layer then top with either the traditional cocoa powder or you can use chocolate chips like we did!
Set the tiramisu cups in the fridge and let it set for 2 hours before serving.