Add the bananas, Greek yogurt, peanut butter, milk, and cinnamon to a high-speed blender. Blend until completely smooth and creamy, scraping down the sides as needed.
Pour the mixture evenly into an ice cream bar mold, insert the sticks, and freeze for at least 6 hours, or until completely firm.
To make the chocolate shell, combine the chocolate chips and coconut oil in a small saucepan over low heat, stirring until mostly melted. If needed, transfer to a microwave-safe bowl and microwave in 10- to 15-second intervals, stirring between each, until completely smooth.
Remove the bars from the molds. Dip each frozen bar into the melted chocolate, allowing the excess to drip off. If desired, immediately sprinkle with chopped almonds or your favorite chopped nuts and a pinch of flaky sea salt before the chocolate hardens.
Place the bars on a parchment-lined tray and return them to the freezer for 5 to 10 minutes to fully set.
Store in an airtight container in the freezer for up to 2 months. Enjoy!