Banana-(Walnut) Chocolate Chunk Cookies

I made these last weekend and they are officially the first thing I baked in the new house. What a joy with so much more counter space. I left the walnuts out because 1.) I didn't have any and 2.) I really just prefer things without nuts. I also used milk chocolate chips instead of the semisweet chocolate chunks. They were still delicious!

1 cup all purpose flour
1/2 cup whole-wheat flour
1 tsp. coarse salt
1/2 tsp. baking soda
3/4 cup unsalted butter, softened
1/2 cup granulated sugar
1/2 cup packed light brown sugar
1 large egg
1-1/2 tsp. pure vanilla extract
1/2 cup mashed ripe banana (about 1 large)
1 cup old-fashioned rolled oats
8 oz. semisweet chocolate, coarsely chopped into 1/4 inch chunks

Preheat oven to 375 degrees. Whisk together flours, salt and baking soda in a small bowl; set aside. Put butter and 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 and walnuts (optional).

Using a 1-1/2 inch ice cream scoop, drop dough onto baking sheets lined with parchment paper, spacing about 2 inches apart. Bake cookies, rotating sheets halfway though, until golden brown and just set, 12-13 minutes. Let cool on sheets on wire racks for 5 minutes. Transfer cookies to wire racks; let cool completely.