Prep your tools. Heat the oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone mats to prevent sticking and help even browning.

Mash the bananas. In a large bowl, mash the bananas with a fork until mostly smooth. A few small lumps are fine; they add texture and moisture.

Whisk in wet ingredients. Add the melted butter, brown sugar, granulated sugar, egg, and vanilla. Whisk until the mixture looks glossy and well combined.

Combine dry ingredients. In a separate bowl, whisk together the flour, baking soda, baking powder, cinnamon, and salt. This prevents clumps and distributes leavening evenly.

Bring it together. Add the dry mixture to the wet mixture. Stir gently with a spatula just until you no longer see streaks of flour. Do not overmix.

Fold in oats and chocolate. Stir in the rolled oats and chocolate chips (and nuts or coconut if using). The dough will be soft and slightly sticky—this is normal.

Optional chill. For thicker cookies, chill the dough for 20–30 minutes. If you’re short on time, you can bake right away. They’ll just spread a bit more.

Scoop and space. Use a tablespoon or a 1.5-tablespoon cookie scoop to portion dough onto the baking sheets, spacing about 2 inches apart. For neater edges, gently pat the scoops into domes.

Bake. Bake for 10–12 minutes, rotating pans halfway through, until the edges are set and lightly golden. The centers may look slightly soft—that’s perfect for a chewy cookie.

Cool. Let the cookies rest on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely. They firm up as they cool, but stay soft.