Place graham crackers into a food processor and pulse until you have fine crumbs. This creates a buttery, crunchy base for your tart.
Transfer the crumbs to a bowl and mix with melted butter and a pinch of sugar if using. Stir until well combined and the mixture looks like wet sand.
Press the crumb mixture evenly into the bottom and up the sides of a 23cm (9-inch) tart pan, making sure it’s compacted and smooth.
Bake the crust in a preheated oven at 180°C (350°F) for about 10 minutes until fragrant and slightly golden. Let it cool completely on a wire rack.
Meanwhile, melt the semi-sweet chocolate and butter together using a double boiler or microwave in 20-second bursts, stirring between each until smooth and glossy.
Spread a generous layer of peanut butter over the cooled crust, using a spatula to smooth it out evenly.
Pour the melted chocolate over the peanut butter layer, gently spreading it with the spatula to create an even, glossy surface.
Sprinkle a pinch of sea salt or chopped peanuts on top for added crunch and flavor contrast. Chill the tart in the fridge for at least 2 hours or until the chocolate is set and firm.
Once set, use a sharp knife to slice the tart into clean pieces. For neat cuts, warm the knife slightly before slicing.
Serve the tart chilled, perhaps with a glass of milk or coffee, and enjoy the velvety layers of chocolate and peanut butter with each bite.