Let us begin.
Step 1: "I'm a banana, I'm a banana, peel the banana, peel the banana" (Family Guy)
The first step is to peel the banana and push your topping into the meat of the fruit. And that is all. You can be however creative as the government allows you to be in this step, add stuff like sprinkles and what-not, other yummy unhealthy things that will make this treat that much more desirable.
Step 2: Make some paste
In this step we will be caramelizing some C6H12O6 (sugar) yum!
To do that you simply melt a block of butter in a pan and add a clump of brown sugar to the concoction and stir on med. heat. Keep stirring and dont stop stirring until it reaches the viscosity of whatever you think caramel should be, if you stop it will burn.
You may also wish to add some cream to make it less grainy.
If your to lazy to make caramel than you can substitute this ingredient for peanut butter, which is probably better anyways.