Preheat the oven to 275℉
Grease a 9x13 cake pan, and set aside.
In a large bowl, combine the egg whites, sugar, and cream of tartar. Using an electric mixer (or KitchenAid), beat the sugar mixture on high speed until it forms stiff peaks, 5-10 min.
Add the vinegar and vanilla extract and beat until well blended. Using a spatula, spread the mixture, trying to keep it as even as possible, in your prepared pan.
Place your pan in the oven and bake until the meringue is firm to the touch but not browned, about 45-60 minutes. Remove the pan from the oven and allow it to cool completely.
If you are using Cool Whip, skip this step. If you are making homemade whipped cream, prep it while your meringue cools. In a medium bowl, combine the heavy cream, powdered sugar, and vanilla. And beat until stiff.
Once the meringue has cooled completely, layer the sliced bananas over the meringue in a single even layer. Top with the Cool Whip or homemade whipped cream.
Banana torte can be served immediately, but personally, I think it's best after it has been refrigerated for 1-2 hours.
Enjoy!