Start by preheating your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat. This helps prevent sticking and makes cleanup easier.

In a large mixing bowl, use a hand mixer or stand mixer to beat the softened butter and brown sugar together until the mixture is light and fluffy about 2 minutes.

Mix in the mashed bananas, egg, and vanilla extract. Beat until well combined. The mixture may look slightly curdled because of the bananas, but that’s totally normal.

In a separate bowl, whisk together the flour, baking soda, salt, cinnamon, and nutmeg. Gradually add the dry mixture into the wet mixture and mix until just combined. Don’t overmix — just stir until there’s no more visible flour.

Using a spatula or spoon, fold in the rolled oats, chopped nuts, and chocolate chips. This will give your cookies that hearty, banana-bread-meets-cookie texture and flavor.

Drop spoonful of dough (about 1 to 1½ tablespoons each) onto your prepared baking sheet, spacing them about 2 inches apart. Bake for 12 to 14 minutes, or until the edges are lightly golden and the centers look set. Let the cookies rest on the pan for 5 minutes before transferring them to a cooling rack.