Line 11x16 jelly roll pan with parchment paper and preheat the oven to 325F.
In a stand mixer with a whisk attachment bead the egg whites till they form soft peaks, slowly add sugar a tablespoon at a time and beat to stiff peaks. Squish some of the mixture between your fingers to check if all the sugar has dissolved, if it’s grain beat for another minute.
In a small dish dissolve the cornstarch with vinegar and vanilla, add in to the egg whites and mix till just combined.
Spread the meringue in the parchment lined pan, you don’t have to spread all the way to the edge of the pan. Try to keep straight lines and an even thickness.
Bake at 325F for 25 min till evenly golden brown. While baking place a towel on the counter, top with a clean sheer of parchment paper and heavily dust with powdered sugar.
Once baked immediately flip meringue onto the sugar coated paper. Peel away the lining paper, pulling the paper off can be tricky so take your time, if some of the meringue comes with it start from another corner as if taking off a sticker. Dust with powdered sugar and add a new piece of parchment, roll the meringue from the short end with the towel rolled into it as a spacer, let cool.
Whip the heavy cream with sugar and vanilla till you almost reach soft peaks.
Unroll the meringue, peel off the parchment paper, hopefully you’ve dusted it enough that it hasn’t stuck.
Slather the surface with whipped cream, evenly layer with sliced bananas, caramel sauce and crushed graham crackers. Roll the meringue back up in the same direction that it wants to go from being previously rolled removing the other sheet of parchment paper as you go.