Line a baking sheet that will fit in your freezer with parchment paper.
Peel the bananas and cut them into rounds about 1/4" (6 mm) thick.
Place about 1/4 teaspoon of peanut butter in the center of half of the banana slices. Don’t spread it to the edges.
Top each peanut butter-covered slice with another banana round. If using runny natural peanut butter, place the top slice gently without pressing down.
Arrange the bites on the prepared baking sheet and freeze for 2-3 hours, or until firm enough to handle.
Add the chocolate, coconut oil, and salt to a very small microwave-safe bowl. Microwave at 50% power in 30-second increments, stirring after each one, until completely melted and smooth.
Working in batches, remove a few banana bites from the freezer and dip each one in the melted chocolate. Return them to the parchment-lined sheet.
Immediately add sprinkles or finely chopped peanuts before the chocolate sets. Leave some plain, if desired.
Repeat with the remaining bites, keeping them frozen until you’re ready to dip them.
Return the finished bites to the freezer until the chocolate has completely set.
Recipe notes
Natural and conventional peanut butter both work. Natural peanut butter is runnier, so be careful not to overfill or press the bites together.
The banana slices should be about 1/4" (6 mm) thick. Thicker slices make the finished bites more difficult to eat and more likely to fall apart.
Use a very small bowl for melting and dipping the chocolate. This creates a deeper pool and makes dipping easier.
Add the toppings immediately after dipping each bite because the chocolate sets quickly on the frozen bananas.
If the banana bites are completely frozen solid, let them sit at room temperature for a few minutes before dipping.
Store in an airtight freezer-safe container for up to 1 month.