01 - Combine the peanut butter and softened cream cheese in a large mixing bowl. Beat with an electric mixer on medium speed until completely smooth and creamy, about 2 minutes.
02 - Add the powdered sugar to the peanut butter mixture. Mix on low speed initially to incorporate, then increase to medium speed and beat until fully blended and no lumps remain.
03 - Gently fold the thawed Cool Whip into the peanut butter mixture using a rubber spatula. Use a light folding motion to maintain airiness and stop as soon as fully combined. Avoid overmixing to preserve the light texture.
04 - Spoon or pipe the mousse evenly into 6 individual serving glasses, ramekins, or dessert bowls. Smooth the tops with the back of a spoon for an even presentation.
05 - Refrigerate the mousse for at least 1 hour to allow it to set and develop the proper creamy texture. For best results, chill up to 4 hours before serving.
06 - Just before serving, top each portion with chopped roasted peanuts and chocolate shavings or mini chocolate chips if desired. Serve chilled.