Preheat oven to 350° and line a 9x13 baking dish with foil with the edges hanging over. Spray with non-stick cooking spray and set aside.
In a large bowl, beat butter and sugar together until light and fluffy.
Add eggs, sour cream and vanilla, and beat until combined.
Next, add flour, baking soda and salt and beat until just combined.
Stir mashed bananas into cake mixture and mix until combined.
Pour cake batter into the prepared pan and bake for 35-40 minutes or until a toothpick inserted in the middle comes out clean.
Remove from the oven and let cool completely.
Carefully grab both sides of the foil and gently pick up the cake out of the baking dish and place on a hard surface.
Slice the cake equally in half lengthwise.
Carefully remove the top layer and then place foil and bottom cake layer back into the baking dish.
Once the cake has cooled completely, remove ice cream from the freezer, remove cardboard from ice cream and add sliced ice cream to the top of the bottom cake layer.
Make sure the ice cream covers the whole bottom layer.
Carefully add the top layer of cake on top of the ice cream.
Cover with plastic wrap and place in the freezer until ready to serve.
Remove cake from the freeze and cut into desired size pieces.
Pour warm hot fudge sauce over each piece of cake and top with whipped cream and a cherry.