Prepare the coffee mixture. Brew 1 cup of strong coffee and let it cool. Mix in 1/6 cup of dark rum (or your choice of brandy or liqueur).
Separate egg yolks from egg whites, then whip the egg whites with a pinch of salt until stiff peaks form. If you turn the bowl over and the whites stay in place, they're done.
Whisk the egg yolks and sugar together until the mixture is light in color and ribbony in consistency.
Gently fold the mascarpone cheese into the egg yolk mixture until smooth and well combined. It's better to use a mixer here.
Gently fold the whipped egg whites into the mascarpone mixture. If your mixer is too intense, try using a spoon instead to ensure the whites don’t deflate in the process. I always use a spoon.
Cut ladyfinger cookies to fit into your cups (in my case into 3 pieces) if needed.
Quickly dip each ladyfinger into the coffee mixture, ensuring they are fully soaked but not falling apart (1-2 seconds per dunk). A quick dunk on each side should be sufficient.
Layer the Tiramisu: In individual serving cups, spread a layer of the mascarpone mixture on the bottom. Arrange a layer of coffee-soaked ladyfingers on top of the mascarpone mixture. Spread another layer of the mascarpone mixture over the ladyfingers. Depending on the height of your cups, you may need to repeat the process with another layer of ladyfingers and finish with a final layer of the mascarpone mixture.
Dust the top of the tiramisu with unsweetened cocoa powder, using a seal to create a thin, even layer.
Chill & Serve: Cover your cups with plastic wrap and refrigerate for at least 3 hours, preferably overnight, to allow the flavors to meld and the dessert to set. Decorate with mint and berries before serving or sometime in advance (2-3 hours max) to be ready to serve them right from the fridge.
Serve your mini Tiramisu dessert cups and enjoy your delicious homemade tiramisu! Be ready to receive compliments from your guests as I’m sure there’s going to be plenty!