Heat oven to 375°F. Place cupcake liners in each muffin cup.
In large bowl, beat eggs and vanilla with electric mixer on medium speed about 30 seconds or until frothy and light yellow. Break up cookie dough into egg mixture; add bananas and baking powder. Beat on medium speed about 1 minute or until smooth and well blended. Gently stir in 1 cup of the walnuts.
Divide batter evenly among muffin cups; sprinkle with remaining 1/2 cup walnuts and the sugar. Bake 24 to 27 minutes or until toothpick inserted in center comes out clean. Cool in pan 5 minutes. Remove muffins from pan to cooling rack. Cool 5 minutes. Serve warm or cool. Store covered.