Place scalding hot water in a bowl, add the jello packet and whisk until the jello dissolves. In a separate larger bowl, beat the cream cheese with an electric mixer until light and fluffy. Scrape the bowl, then slowly add the warm jello mixture into the cream cheese and beat until there are no clumps.
Allow the jello mixture to cool to room temperature, then fold in the cool whip.
Line a 8x11-inch pan with foil. Place 6 whole graham crackers at the bottom of the pan, creating a flat, tight layer. Spoon 1/3 of the jello mousse over the graham crackers and smooth. Repeat with remaining crackers and jello mousse until you have three layers of cracker and three layers of mousse in the jello cake recipe.
Place in the fridge to cool for at least two hours, to set the mousse and soften the graham crackers. Lift the jello cake out of the pan with the edges of the foil. Trim the messy edges and cut into 12 pieces. Garnish and serve.
NOTES: The nutritional facts are calculated with full-fat cream cheese and cool whip. However, low-fat substitutions can easily be made.