Prep your pan and oven. Heat the oven to 350°F (175°C). Line two baking sheets with parchment paper to prevent sticking and encourage even browning.

Mash the bananas. In a large bowl, mash 2 ripe bananas with a fork until mostly smooth. A few small lumps are fine. You should have about 3/4 cup of mashed banana.

Add wet ingredients. Whisk in 1/3 cup melted butter (or coconut oil), 1/3 cup brown sugar, 1 large egg, and 1 teaspoon vanilla extract. Mix until the mixture is cohesive and glossy.

Combine the dry ingredients. In a separate bowl, stir together 1 cup all-purpose flour, 1 1/2 cups rolled oats, 1/2 teaspoon baking soda, 1/2 teaspoon ground cinnamon, and 1/2 teaspoon salt.

Bring it all together. Add the dry ingredients to the wet and fold gently with a spatula until just combined. Do not overmix. Fold in 3/4 to 1 cup chocolate chips and, if using, 1/2 cup chopped nuts.

Rest the dough. Let the dough sit for 5–10 minutes. This allows the oats to hydrate, which helps the cookies hold their shape and bake up tender.

Scoop the cookies. Use a medium cookie scoop or tablespoon to portion 2-tablespoon mounds onto the prepared sheets, spacing about 2 inches apart. For neater edges, lightly flatten the tops with damp fingers.

Bake. Bake for 10–12 minutes, rotating the pans halfway through. The edges should look set and lightly golden, and the centers should appear slightly soft.

Cool. Let the cookies rest on the baking sheet for 5 minutes, then transfer to a rack to cool completely. They’ll firm up as they cool while staying soft inside.

Enjoy. Serve warm for melty chocolate or room temperature for a chewier bite. A sprinkle of flaky salt on top is a nice finishing touch.