In a large mixing bowl, beat 1 cup of heavy cream using an electric mixer on medium speed until soft peaks form, about 3-5 minutes.

Add 8 ounces of mascarpone cheese, 1/2 cup of powdered sugar, and 1 teaspoon of vanilla extract to the whipped cream. Continue mixing on medium speed until stiff peaks form, about 2-3 minutes.

Arrange a single layer of ladyfingers in a 9x13 inch baking dish, fitting them snugly together.

Gently brush half of the 1/2 cup of orange juice over the ladyfingers, ensuring an even coating.

Spread half of the mascarpone mixture over the moistened ladyfingers.

Thinly slice 2 ripe bananas and layer them over the mascarpone mixture.

Repeat the process: place another layer of ladyfingers, brush with remaining orange juice, and spread the rest of the mascarpone mixture on top, followed by another layer of banana slices.

Spread 1 cup of Cool Whip evenly over the top layer of banana slices, smoothing it out.

Cover the dish tightly with plastic wrap and refrigerate for at least 4 hours, preferably overnight.

Before serving, remove the plastic wrap and garnish with additional banana slices.