In large bowl, break up softened cookie dough. Beat with electric mixer on low speed 30 seconds. Add remaining 2 tablespoons oil, the egg and mashed banana. Beat on low speed 1 minute, scraping bowl as needed. Add 1/2 cup of the flour, the baking powder and 1/8 teaspoon salt. Beat on low speed 30 seconds, scraping bowl as needed. Beat on medium speed 1 minute. Gently stir in chopped banana. Divide batter evenly among muffin cups (cups will be full).