Preheat the oven to 350 degrees F.
In a medium nonstick pot on the stove, combine sugar, cornstarch, cinnamon, vanilla extract, and salt with 1/2 cup cold water. Mix until the ingredients dissolve. Add apples and stir. Bring to medium-high heat and, stirring frequently, cook until apples have softened, about 7 to 10 minutes.
Reduce heat to low and, stirring often, cook until thick and gooey, 1 to 2 additional minutes. Transfer to a bowl and set aside to cool. This is your pie filling.
Prepare a large baking sheet by lining it with foil and/or spraying it with nonstick spray. Set aside.
Place egg roll wrappers flat on a dry surface. Set out a small dish of water. Dip your finger into the water, and run it along all of the wrapper edges. Cook's Note: Repeat as needed while preparing your pockets, as it will help seal them. Starting 1/2 inch from the bottom, place about 1/3 cup pie filling along the bottom half of each wrapper, leaving a 1/2-inch border on the sides.
Fold the top 1/2 of each wrapper over the filling, so that the top edge meets the bottom and the filling is encased with a border on 3 sides. Dab each border with water, and fold each inward about 1/4 inch to lightly seal. Press firmly along the borders with the prongs of a fork to seal completely.
Carefully transfer to the baking sheet. Repeat this process with remaining wrappers and filling, leaving you with 6 pie-lets.
Spray the top of each pocket with 3 sprays butter. Bake in the oven until the edges begin to brown, 15 to 18 minutes.
Allow to cool for 5 minutes. Top with additional cinnamon and whipped topping, if using. Dig in!
PER SERVING (1 pie-let): 110 calories, 0.5g fat, 156mg sodium, 25g carbs, 1.25g fiber, 10.5g sugars, 2g protein