Preheat the oven to 350 degrees F (175 degrees C).

In a medium bowl, mix together the graham cracker crumbs, 1/4 cup sugar, and melted margarine. Press into the bottom of a greased 9x13 inch baking dish.

In another bowl, mix together the cream cheese and 3/4 cup sugar until smooth. Blend in the eggs one at a time, then stir in the vanilla and mashed banana. Pour into the prepared crust.

Bake for 30 minutes in the preheated oven, or until the center is set. Cool, and refrigerate for at least 3 hours.

Combine evaporated milk and caramels in a saucepan over medium heat. Cook stirring frequently until caramels are melted and the mixture is smooth. Garnish the cheesecake with banana slices, and drizzle caramel sauce over.