These easy Banana Walnut Chocolate Chip Cookies are the perfect way to use up that lone brown banana. They are soft, slightly chewy, and super banana-y. Meanwhile, the addition of oatmeal provides a wonderful texture and flavor that is somewhat reminiscent of freshly baked muffins!
Preheat oven to 375°F. Whisk together both flours, salt, and baking soda in a bowl.
Put butter and both sugars into the bowl of an electric mixer fitted with the paddle attachment; mix on medium speed until pale and fluffy. Reduce speed to low. Add egg and vanilla; mix until combined. Mix in banana. Add flour mixture; mix until just combined. Stir in oats, chocolate chips, and walnuts.
Using a 1 ½-inch ice cream scoop (#40 size), drop dough onto baking sheets lined with parchment paper, spacing about 2 inches apart (you’ll need 3 half sheet pans). Bake cookies, rotating sheets halfway through, until golden brown and just set, 11 to 13 minutes. Let cool on sheets on wire racks 5 minutes. Transfer cookies to wire racks; cool completely. Cookies can be stored in airtight containers at room temperature up to 2 days.
To freeze: scoop out the dough as you would to bake. Freeze the scooped balls of dough until frozen solid. Transfer the frozen balls into a freezer bag, and label with the date. Frozen cookie dough can last about 3 months in the freezer. When ready to bake, remove as many balls of dough as you desire, and partially thaw them in the refrigerator (you can bake from a frozen state, but I always feel like they don’t spread out as nicely). Bake as directed in the recipe. You may need an extra minute or two of baking time since the dough will be cold or even partially frozen.