01 - Line a rimmed baking sheet with parchment paper and set aside.
02 - Peel the bananas and cut into ΒΌ-inch thick rounds. Arrange the slices in a single, slightly overlapping layer to form a rough rectangle on the prepared baking sheet.
03 - Place the chopped chocolate in a microwave-safe bowl and heat in 20-second intervals, stirring between each burst, until completely smooth and glossy. Alternatively, melt using a double boiler over simmering water.
04 - Pour the melted chocolate evenly over the arranged banana slices, using a spatula to gently spread and cover every edge.
05 - Drizzle the peanut butter over the chocolate layer if using. Sprinkle the chopped roasted nuts, mini chocolate chips or cacao nibs, and flaky sea salt evenly across the surface.
06 - Transfer the baking sheet to the freezer and chill for at least 45 to 60 minutes, or until the bark is completely firm and set.
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 from the freezer for the best crunchy texture.