Lay a piece of parchment paper onto a cookie sheet.
Thinly slice your 2 bananas and arrange them on the sheet so that they are all touching.
Pour over your peanut butter. You can always warm up the peanut butter slightly to make it more runny.
Place into the freezer for 30-60 minutes or until partially frozen.
Meanwhile, melt together the dark chocolate with the coconut oil.
Spread chocolate in a thin layer over banana and peanut butter mixture. You'll have to work quickly as it will harden fast. Immediately sprinkle chopped peanuts over top. Sprinkle with sea salt if desired.
Place back in freezer until it's all frozen.
Remove from freezer and take parchment out of the baking sheet. Gently loosen the bark from the parchment. With a large knife, slice into 12 pieces.
Store in freezer.