Preheat oven to 350°. Spray a 9-inch square baking pan with cooking spray.
In a medium bowl, stir together graham cracker crumbs, melted butter, pecans, 2 tablespoons sugar, ½ teaspoon cinnamon, and ¼ teaspoon salt until combined. Using the bottom of a measuring cup, firmly press mixture into bottom of prepared pan.
Bake until lightly browned, about 12 minutes. Let cool completely on a wire rack. Leave oven on.
In a small microwave-safe bowl, heat chocolate on high in 15-second intervals, stirring between each, until melted and smooth. Spread onto cooled crust. Freeze until firm, about 15 minutes.
In a medium bowl, whisk together sweet potato, milk, eggs, ginger, remaining ¾ cup sugar, remaining 1 teaspoon salt, and remaining 1 teaspoon cinnamon until smooth. Spread onto chocolate layer.
Bake until center is set, 45 to 50 minutes. Let cool completely on a wire rack. Refrigerate until cold, about 3 hours.
Preheat oven to 350°.
Sprinkle marshmallows onto sweet potato layer.
Bake until marshmallows are lightly toasted, about 5 minutes. Cut into 3-inch squares, and serve immediately.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/sweet-potato-smores-bars-recipe/