Preheat the oven to 300° F.
Line a baking tray with parchment paper or spread a thin layer of oil.
Mix banana together with the oil, honey, and cinnamon.
Stir in the oats until everything is well combined.
Spread the granola mixture out on the baking tray.
Make sure the mixture spreads thin and evenly, otherwise some of it will burn (use multiple baking trays if necessary).
Bake for 60 minutes, mixing it thoroughly every 15 minutes, until the mixture starts to turn golden brown.
Allow to cook until granola hardens.
To cool quickly, place the baking tray in the fridge or freezer.