Preheat the oven and prepare the pan. Set your oven to 350°F (175°C).
Line a baking sheet with parchment paper or a silicone mat so the cookies release easily.
Mash the bananas. In a medium bowl, mash the bananas with a fork until mostly smooth with just a few small lumps. The smoother the mash, the softer the cookies.
Stir in wet ingredients. Add the nut or seed butter, oil (if using), and vanilla. Mix until the banana mixture looks creamy and uniform.
Add dry ingredients. Sprinkle in the oats, cinnamon, baking powder, and salt if using.
Stir until the oats are evenly moistened and the mixture holds together. If it seems too wet, add a tablespoon more oats; too dry, add a teaspoon of water or a bit more mashed banana.
Fold in optional add-ins. If using raisins, mini chips, or seeds, fold them in gently. Keep pieces small for toddler safety.
Portion the cookies. Scoop tablespoon-sized mounds onto the baking sheet.
Use damp fingers to press and flatten each mound to about 1/2 inch thick. Thinner cookies bake more evenly and stay soft.
Bake. Bake for 10–13 minutes, until the edges feel set and the tops look dry. They won’t brown much, so rely on texture more than color.
Cool. Let the cookies cool on the pan for 5 minutes, then transfer to a rack.
Cooling helps them firm up to the perfect soft-chewy texture.
Serve. Offer whole cookies or break into small pieces for younger toddlers. Always supervise while they eat.