Preheat oven to 350 degrees Fahrenheit and grease a 9x13" cake pan. In the bowl of an electric mixer, add the Kodiak Cakes All-Purpose Baking Mix, egg, brown sugar, baking powder, baking soda, cinnamon, nutmeg, vanilla, canned pumpkin, softened butter and 1 c. chocolate chunks. Mix until incorporated and press into prepared pan. Sprinkle and press remaining 1/2 cup chocolate chunks on top.