Prep your pan and oven. Heat the oven to 350°F (175°C).
Line a baking sheet with parchment paper or a silicone mat to prevent sticking.
Mash the bananas. In a large bowl, mash the bananas with a fork until mostly smooth with small lumps. The smoother the mash, the softer the cookies.
Combine dry ingredients. Stir in the oats, cinnamon, ground flax or chia (if using), and a small pinch of salt. Add vanilla and applesauce if you like.
Fold in mix-ins. If using raisins, coconut, or seed butter, fold them in gently.
Keep pieces small for toddler-friendly bites.
Check the texture. The dough should be thick and scoopable, not runny. If it feels too wet, add a few tablespoons of oats. If too dry, mix in a little more mashed banana or applesauce.
Portion the cookies. Scoop heaping tablespoons onto the baking sheet.
Use damp fingers to press each mound into a flat, round cookie about 1/2 inch thick. Flattening helps them bake evenly and stay soft.
Bake. Bake for 12–15 minutes, until the edges are set and the tops look dry. They won’t brown much, and that’s okay.
Cool completely. Let the cookies cool on the pan for 5 minutes, then move to a rack to cool fully.
Cooling helps them firm up to the perfect soft-chewy texture.
Serve. Offer plain or with a thin smear of yogurt or seed butter for dipping. Always cut or break into small pieces for younger toddlers as needed.