Step 1: Prepare the Cake

1. Preheat the oven to 350°F (175°C) and grease a 9×13-inch baking dish.
2. In a large bowl, combine the chocolate cake mix, water, vegetable oil, and eggs. Mix according to the package instructions until well combined.
3. Pour the batter into the prepared baking dish and bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake to cool completely in the pan.

Step 2: Make the Peanut Butter Layer

1. In a medium bowl, beat together the softened cream cheese, peanut butter, powdered sugar, and vanilla extract until smooth and creamy.
2. Gently fold in the whipped topping until well combined.
3. Once the cake has cooled, spread the peanut butter layer evenly over the top.

Step 3: Prepare the Chocolate Topping

1. In a small saucepan over medium heat, heat the heavy cream until it just begins to simmer.
2. Remove from heat and add the semi-sweet chocolate chips. Let sit for a few minutes, then stir until smooth and fully melted.
3. Drizzle the chocolate topping over the peanut butter layer, spreading it evenly if needed.

Step 4: Chill and Serve

1. Refrigerate the cake for at least 2 hours to allow the layers to set.
2. Before serving, sprinkle chopped peanuts on top if desired.
3. Cut into squares and serve cold.