Spray a 9-inch pie dish with vegetable oil spray. Line the sides with whole Popcorners. Break the remainder and sprinkle them over the bottom of the pie dish.
In a medium saucepan, stir together the sugar and water. Bring to a boil over medium-high heat and let cook until the sugar turns a deep amber. Stir in the ¼ cup heavy cream – be careful because it will bubble up and might splatter. Reduce the heat to low and stir until the caramel is smooth.
Remove from heat and stir in the butter until completely melted and blended. Set aside to cool for 10 minutes.
Slice the bananas over the Popcorner crust.
Spoon the caramel over the bananas. Spoon the vanilla filling into the pie, smooth the top, cover with plastic wrap and refrigerate for at least 2hours.
When ready to eat, whip the 1 cup heavy cream until it is stiff. Cover the top of the pie with swirls of cream, cut into wedges and serve.