01 - Line an 8x12 inch baking sheet with parchment paper, ensuring complete coverage to prevent sticking.
02 - Melt the chopped dark chocolate in a heatproof bowl set over a saucepan of gently simmering water, stirring frequently until completely smooth and glossy. Alternatively, microwave in 30-second intervals, stirring between each interval.
03 - Pour the melted chocolate onto the prepared baking sheet. Use an offset spatula or the back of a spoon to spread it into an even layer approximately 1/4 inch thick.
04 - Warm the peanut butter in the microwave for 10-15 seconds until it becomes fluid and easily pourable. Do not overheat.
05 - Drizzle the warmed peanut butter over the chocolate surface in thin parallel lines or scattered dollops. Immediately use a skewer or knife tip to gently swirl through both layers, creating a marbled effect without over-mixing.
06 - While the chocolate remains soft, immediately sprinkle the surface with chopped peanuts, flaky sea salt, and any additional toppings of your choice. Press lightly to ensure adherence.
07 - Transfer the baking sheet to the refrigerator and chill for at least 30 minutes, or until the bark is completely firm and breaks cleanly when tested.
08 - Remove the bark from the refrigerator and break it into irregular pieces. Store in an airtight container at room temperature for up to 1 week, or refrigerate for extended freshness.