Chill a mixing bowl and beaters in the refrigerator for about 15 minutes. Pour in the heavy whipping cream and beat on high speed until soft peaks form (2-3 minutes).

Fold in the mascarpone cheese, powdered sugar, and vanilla extract into the whipped cream until smooth and thick (2-3 minutes).

Lay the ladyfingers in a single layer at the bottom of a 9x13 baking dish.

Brush half of the orange juice evenly over the ladyfingers, allowing 3-5 minutes for them to soak up the juice.

Spread half of the mascarpone mixture over the soaked ladyfingers, and add sliced bananas on top.

Repeat with a second layer of ladyfingers soaked in orange juice, followed by the rest of the mascarpone mixture and banana slices.

Top with Cool Whip, smooth it out, cover with plastic wrap, and refrigerate for at least 4 hours, preferably overnight.

Serve by slicing into squares or spooning into cups, garnishing with additional banana slices if desired.