Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or lightly grease it with non-stick spray.
Mash the bananas in a large mixing bowl using a fork. Keep mashing until you get a smooth, lump-free paste — this is both your sweetener and your binder.
Add oats and raisins to the mashed banana. Stir everything together until fully combined. The dough will be soft and sticky — that's perfect.
Scoop the dough onto the prepared baking sheet using a tablespoon or cookie scoop. Flatten each mound slightly with the back of the spoon — these cookies don't spread on their own.
Bake for 13–15 minutes, or until the edges turn golden and the tops look set. They will feel slightly soft when you take them out — they firm up as they cool.
Cool completely on the tray for at least 5 minutes before lifting. Enjoy warm or store for later.
