Prepare the Baking Sheet:
Line a medium-sized baking sheet with parchment paper.
Slice the Bananas:
Peel and slice the bananas into ⅓-inch thick slices. For a better fit, slice them on a slight angle. Ensure the slices are as even in size as possible.
Arrange the Banana Slices:
Place the banana slices on the lined baking sheet, arranging them in a rectangular shape. Make sure the slices are touching to help them hold together when frozen.
Spread the Peanut Butter:
Evenly spread the peanut butter over the banana slices to cover them completely. If the peanut butter is too thick, microwave it in a microwave-safe dish for 10-15 seconds to make it easier to spread. Use a rubber spatula for smooth application. Place the baking sheet in the freezer for 20 minutes to set.
Melt the Chocolate:
After 20 minutes, add the dark chocolate chips to a microwave-safe dish. Heat in 30-second intervals, stirring in between until the chocolate is mostly melted. Then stir until fully melted. If using, add the coconut oil to help with smoothness. Watch carefully to avoid burning the chocolate.
Assemble the Bark:
Remove the banana bark from the freezer. Pour and spread the melted chocolate evenly over the peanut butter layer. If desired, sprinkle with flaky sea salt or other toppings.
Freeze and Serve:
Place the bark back into the freezer for at least 90 minutes, or up to 2 hours, until fully set. Once ready, remove the bark from the freezer, flip it over, and peel off the parchment paper. Break the bark into large pieces, serve, and enjoy!