Grease an 8x8 baking dish with butter or shortening. Set aside.

In a large bowl, add the mascarpone, cream cheese, sugar, and vanilla extract. Beat everything together using an electric hand mixer at medium speed until smooth.

With a wooden spoon or spatula, fold in the thawed whipped topping until just mixed. Set the mascarpone mixture aside.

Pour the espresso into a shallow bowl or dish. Quickly dip one ladyfinger at a time into the espresso, flip it over, and place it in the base of the 8x8 baking dish. Repeat with about 8 more ladyfingers or until the entire base of the baking dish is covered. (Break some of the ladyfingers in half if you need to fill in smaller spaces.)

Spoon about half of the mascarpone mixture over the ladyfingers, and spread it out evenly.

Dip the remaining ladyfingers into the espresso, and lay them on top of the mascarpone layer.

Spread the rest of the mascarpone mixture over the second layer of ladyfingers, and smooth the top with a spatula. Cover with plastic wrap, and place in the refrigerator for at least 4 hours or until the tiramisu is set. (Overnight is best.)

Dust the cocoa powder over the tiramisu before serving.