Garnish each with remaining toffee bits and a vanilla wafer.
In a large saucepan, add sugar and cornstarch, and stir together.
Whisk in milk and place over medium heat, stirring often.
Bring mixture to a boil and cook stirring constantly 2 minutes.
Remove from heat and pour 1 cup of mixture into egg yolks, quickly stirring as you pour.
Stir egg mixture into pudding mixture and return to heat.
Bring to a boil, stirring constantly and cook 2 minutes.
Remove from heat and stir in butter and vanilla.
Place 3 cookies in each of 6 (8 oz) bowls.
Top each with about ½ cup of pudding.
Slice bananas and layer half of each banana over pudding.
Spoon 1 tablespoon caramel over bananas, sprinkle with toffee bits.
Add 3 more cookies to each bowl, top with about ½ cup pudding.
Top each with whipped topping.