Line a baking sheet or flat plate with parchment paper.
Arrange the banana slices in a single layer, touching each other to form a cohesive rectangular block.
Spread the peanut butter evenly over the top of the banana slices using an offset spatula.
In a microwave-safe bowl, combine chocolate chips and coconut oil. Heat in 30-second intervals, stirring between each, until completely smooth.
Pour the melted chocolate over the peanut butter layer and spread to the edges to seal.
Sprinkle flaky sea salt over the wet chocolate.
Place in the freezer for a minimum of 60 minutes or until the chocolate is firm and bananas are frozen.
Break or cut into 5 equal portions and serve immediately.