Preheat your oven to 175°C (350°F). Crush the graham crackers into fine crumbs using a food processor, then transfer to a bowl. Mix the crumbs with melted butter until evenly coated, creating a crumbly dough.
Press the crumb mixture evenly into a 23cm tart pan, covering the base and sides. Use the back of a spoon or your fingers to smooth it out, then bake for 10 minutes until golden and fragrant. Remove from the oven and let cool slightly.
While the crust bakes, melt the dark chocolate slowly over a double boiler or in short bursts in the microwave, stirring until smooth and glossy. Set aside to cool slightly.
In a mixing bowl, whisk together the peanut butter, softened cream cheese, and powdered sugar until the mixture is smooth, creamy, and well combined. This creates a luscious filling that’s easy to spread.
Pour the peanut butter filling into the cooled crust, spreading it out evenly with a spatula. Smooth the top for a clean finish.
Drizzle the melted chocolate over the peanut butter layer, using a spoon or piping bag to create a marbled or even finish. Allow the chocolate to set for about 30 minutes at room temperature or 15 minutes in the fridge.
Place the tart in the refrigerator for at least 2 hours or overnight to fully set and develop flavor. When ready to serve, sprinkle with chopped peanuts or chocolate shavings for added texture and visual appeal.
Before slicing, dip a sharp knife in hot water and wipe dry to ensure clean cuts. Slice the tart into wedges and serve chilled or at room temperature, enjoying the rich, velvety layers with a crisp crust.