Step 1: Brew 1.5 cups of strong espresso and set it aside in a shallow bowl to cool completely to room temperature.
Step 2: In a large mixing bowl, beat the room-temperature mascarpone cheese until smooth and creamy.
Step 3: In a separate chilled bowl, whip the heavy cream, sugar, and vanilla extract until stiff peaks form.
Step 4: Gently fold the whipped cream into the mascarpone cheese using a spatula until fully combined and light.
Step 5: Briefly dip each ladyfinger into the cooled espresso (1-2 seconds) and place them in a single layer at the bottom of a 9x9 inch dish.
Step 6: Spread half of the mascarpone mixture over the ladyfingers, followed by a layer of sliced bananas.
Step 7: Repeat with another layer of dipped ladyfingers and the remaining cream. Cover and chill for at least 6 hours.
Step 8: Dust with cocoa powder just before serving and enjoy your Banana Tiramisu.