Line a baking sheet or large plate with parchment paper or a silicone mat for easy cleanup.
Peel the bananas and slice them into 1/2-inch thick rounds. You should get about 16 slices total from 2 bananas.
Spread a small dollop (about 1 teaspoon) of peanut butter onto half of the banana slices. Top each with another banana slice to create a "sandwich." Place the sandwiches on the prepared baking sheet.
In a microwave-safe bowl, combine the chocolate chips and coconut oil (if using). Microwave in 20-second intervals, stirring between each, until the chocolate is fully melted and smooth. Alternatively, melt over a double boiler on the stovetop.
Dip each banana sandwich halfway into the melted chocolate, or use a spoon to drizzle chocolate over the top. Place them back on the baking sheet. If desired, sprinkle chopped peanuts or sprinkles over the chocolate before it sets.
Freeze the bites for 10-15 minutes, or until the chocolate hardens. Serve chilled or let them sit at room temperature for a few minutes for a softer bite. Enjoy your peanut butter banana bites!