Line a tray with parchment and make room for it in the freezer. Peel bananas and cut into rounds about 1/2 inch thick.
Arrange rounds in a single layer without touching. Freeze for at least 1 hour, until firm enough to lift and dip without bending.
Melt chocolate and coconut oil in a dry microwave-safe bowl in 20-second bursts, stirring between each until smooth.
Let the chocolate cool slightly while remaining fluid. Set optional chopped nuts or coconut nearby before taking the bananas from the freezer.
Working with a few rounds at a time, lower each into chocolate using a fork. Lift, let excess drip away, and slide onto the lined tray.
Sprinkle optional topping immediately, before the cold fruit makes the chocolate set. Return completed bites to the freezer while coating the next group.
Freeze the coated bites for at least 2 hours until firm. Transfer to a sealed container with parchment between layers once the shells are fully set.
Let portions stand 2–3 minutes before eating if very hard. Serve only what you need and keep the rest frozen to protect the chocolate shell.
