Prepare the Base: Grind the cookies in a food processor until fine crumbs form. Mix thoroughly with melted butter and crushed peanuts until well combined. Press this mixture firmly into the bottom and sides of a bûche (log) mold to create a solid base. Place in the freezer for 10-15 minutes to set.
Make the Caramel: Place the sugar in a pan over medium heat and allow it to melt without stirring. Once it turns amber in color, carefully add the butter and stir until incorporated. Gradually pour in the cream (be cautious as it will bubble vigorously). Add a teaspoon of salt and stir to combine. Remove from heat and set aside to cool. The ideal consistency should be smooth and pourable but not too thin.
Prepare the Vanilla Cream: Whip the cold cream until it reaches semi-stiff peaks. Add the mascarpone, powdered sugar, and vanilla, continuing to whip until the mixture becomes shiny and smooth. Incorporate a pinch of salt to enhance the flavor profile.
Assemble the Log: Spread a thin, even layer of peanut butter over the chilled biscuit base. Drizzle a light layer of the cooled caramel sauce over the peanut butter. Pour half of the prepared vanilla cream on top and spread evenly. Sprinkle with roasted peanuts, then add the remaining vanilla cream, smoothing the surface. Cover the log with plastic wrap and refrigerate for at least 6 hours, preferably overnight.
Make the Ganache: Heat the cream in a saucepan until hot but not boiling. Place the finely chopped chocolate in a bowl and pour the hot cream over it. Let sit undisturbed for 1 minute to allow the chocolate to melt. Stir gently until smooth, then incorporate the butter. Allow the ganache to cool slightly before pouring it over the chilled log.
Decorate: Once the ganache has slightly set, add decorative elements like peanut crumbs, caramel drizzle lines, chocolate pieces, and gold dust or sprinkles for a festive touch. For a gourmet enhancement, sprinkle a very fine layer of salt on top to elevate the flavor profile.