Using a hand mixer or stand mixer fitted with a whisk attachment, beat heavy cream and powdered sugar for several minutes, until stiff peaks are just starting to form. Set aside.

Using a hand mixer or a stand mixer with the paddle attachment, beat cream cheese, peanut butter, powdered sugar, and heavy cream. Start on low speed, then gradually increase the speed to medium. Beat for about a minute, until smooth and creamy.

Take half of the prepared whipped cream and fold it into the peanut butter cream, folding until no streaks remain. Set aside the remaining half of whipped cream for the topping.

Spread 1/4 cup of peanut butter cream into the bottom of an 8x8 baking dish. Top with one even layer of graham crackers, breaking pieces to fill in the spaces (I used about 4 1/2 sheets per layer). Top the graham crackers with one fourth of the remaining peanut butter cream, spreading evenly. Top the peanut butter cream with 1/3 cup hot fudge, spreading evenly. Repeat two more times (graham cracker, peanut butter cream, fudge, graham cracker, peanut butter cream, fudge). Then place the fourth and final layer of graham crackers, followed by the final portion of peanut butter cream. Finish by spreading the top with the reserved whipped cream. Cover the baking dish and place in the refrigerator overnight (the longer this sits, the softer the graham crackers will become).

Right before serving, drizzle the top with hot fudge sauce and sprinkle with peanuts. Serve each slice with additional hot fudge, if desired.