Combine graham cracker crumbs and melted butter in a bowl, mixing until the crumbs are fully coated.
Press the mixture firmly into the bottom of a 9x13-inch baking pan to form a crust.
In a separate bowl, blend cream cheese, whipped topping, and 1 cup of sugar until smooth and creamy.
Spread this mixture evenly over the crust.
In a saucepan over medium heat, mix 1 cup of sugar, water, cornstarch, and salt, cooking and stirring until the mixture turns clear, about 3 to 5 minutes.
Add mashed huckleberries, lemon juice, and optional red food coloring, then simmer until the mixture thickens, approximately 5 minutes.
Spread the huckleberry mixture over the cream cheese layer and sprinkle whole huckleberries on top.