01 - Line a rimmed baking sheet with parchment paper, ensuring the paper lies flat across the surface.
02 - Peel the bananas and cut them into ¼-inch thick rounds. Arrange the slices in a single, slightly overlapping layer on the prepared sheet, forming a rough rectangle approximately 8×10 inches.
03 - Place the chopped chocolate in a microwave-safe bowl and heat in 20-second intervals, stirring thoroughly between each burst, until completely smooth and glossy. Alternatively, melt using a double boiler over gently simmering water.
04 - Pour the melted chocolate evenly over the arranged banana slices. Using an offset spatula, gently spread the chocolate to cover every exposed edge and surface.
05 - Drizzle the peanut butter, if using, in thin stripes over the chocolate layer. Immediately scatter the chopped roasted nuts, mini chocolate chips or cacao nibs, and a light pinch of flaky sea salt across the surface.
06 - Transfer the baking sheet to the freezer and chill for at least 45 to 60 minutes, or until the chocolate is completely firm and hardened throughout.
07 - Remove from the freezer and break the bark into irregular pieces by hand, or use a sharp knife to cut into neat squares. Serve immediately while still cold for the best snap and texture.