1. Begin by dissolving the lemon Jell-O in 1 cup of boiling water. Allow it to cool until it slightly thickens.
2. In a large mixing bowl, combine the graham cracker crumbs and melted butter. Add powdered sugar if you prefer a sweeter crust.
3. Press the graham cracker mixture evenly into the bottom of a 9×13-inch or 8×8-inch baking dish to form the crust.
4. In a separate bowl, beat together the softened cream cheese, granulated sugar, and lemon juice (or vanilla extract) until smooth and creamy.
5. Chill the evaporated milk thoroughly, placing the bowl and whisk in the freezer for a short time before whipping for optimal results.
6. Whip the chilled evaporated milk or heavy whipping cream until soft peaks form.
7. Gently fold the whipped milk into the cream cheese mixture along with the cooled and thickened Jell-O. Mix until incorporated.
8. Spread the creamy filling evenly over the prepared crust using a spatula for a smooth finish.
9. Sprinkle a reserved handful of graham cracker crumbs over the top of the cheesecake for decoration, if desired.
10. Cover the baking dish and refrigerate the cheesecake for at least 2 hours, or preferably overnight, to allow it to set fully.
11. Once set, slice the cheesecake into portions and serve.