Line the bottom of a square pan with parchment paper.
Put half of the oats into the food processor and pulse for 2 seconds. Combine with the rest of the oats in a large mixing bowl.
In the separate bowl, mash banana with the fork. Add syrup, vanilla extract and peanut butter. Mix until smooth.
Add the mixture into oats and stir until evenly combined.
Transfer mixture to a prepared pan. Press down using the second sheet of parchment to press it evenly into the bottom of the pan. Freeze for 15 minutes.