Line an 8×8-inch baking dish with two crisscrossed strips of parchment paper, leaving overhang for easy lifting.
Stir together the graham cracker crumbs, granulated sugar, and melted butter until it resembles wet sand. Press firmly and evenly into the bottom of the pan and place in the freezer to chill.
In a large bowl, beat the softened cream cheese until smooth and light, 2 to 3 minutes.
Add the powdered sugar, orange juice concentrate, vanilla, and salt, and beat until creamy. Fold in 1 1/2 cups of the whipped topping.
Spread half of the filling over the chilled crust, smoothing into the corners.
Add the orange gelatin powder to the remaining filling and beat on medium speed until blended, orange in color, and slightly thickened, 1 to 2 minutes. Gently spread over the cream cheese layer.
Spread the remaining 1 1/2 cups whipped topping evenly over the orange layer.
Cover and refrigerate at least 4 hours or overnight, until set.
Lift out using the parchment and cut into bars. Garnish with orange zest or slices, if desired.