Peel the bananas and slice them into 1/2-inch thick rounds.
In a medium bowl, mix together the peanut butter, rolled oats, vanilla extract, and cinnamon until well combined.
If using, fold in the mini chocolate chips and chopped nuts.
Take a slice of banana and spread a generous amount of the peanut butter mixture on top. Place another banana slice on top to create a sandwich.
Repeat this process until all banana slices are used.
Arrange the banana bites on a baking sheet lined with parchment paper.
Freeze the banana bites for at least 1 hour or until firm.
Once frozen, transfer the bites to an airtight container and store in the freezer.