Preheat the oven. Set it to 350°F (175°C). Line a baking sheet with parchment paper to prevent sticking and make cleanup easy.
Mash the bananas. In a medium bowl, mash the bananas with a fork until mostly smooth with just a few small lumps.
You should have about 3/4 to 1 cup of mashed banana.
Add flavor boosters. Stir in cinnamon and vanilla if using. These simple touches give the cookies a warm, cozy taste.
Stir in the oats. Add 1 cup of rolled oats and mix. If the mixture looks very wet, sprinkle in up to 1/4 cup more oats.
The batter should be thick and scoopable, not runny.
Add nut or seed butter (optional). Stir in 1–2 tablespoons for extra protein, healthy fats, and a creamier texture. This also helps the cookies hold together.
Fold in tiny add-ins. If using, stir in finely chopped fruit, raisins, or a small handful of mini chips for older toddlers. Keep pieces very small to avoid choking hazards.
Portion the dough. Scoop tablespoon-sized mounds onto the lined baking sheet.
Gently press each one flat with the back of a spoon; they won’t spread much in the oven.
Bake. Bake for 10–14 minutes, until set around the edges and lightly golden on the bottom. They should feel soft but not sticky on top.
Cool completely. Let the cookies cool on the pan for 5 minutes, then transfer to a rack. Cooling helps them firm up and makes them easier for little hands to hold.