Preheat oven to 350°F. Place all ingredients except walnuts and frosting into mixing bowl. Beat on low speed until blended. Then beat on medium speed for 2 minutes. Add optional walnuts beat until mixed.
Line cupcake pan with liners. Fill cupcake cups 2/3 full.
Bake for 24 minutes or until toothpick inserted into middle comes out clean. Cool and frost with cream cheese frosting.