Preheat oven to 350°. Spray cups and tos of 24-cup mini-muffin pan with nonstick cooking spray; set aside.
Combine 1/2 cup flour, 1/3 cup sugar, 1/4 cup Hellmann's® or Best Foods® Real Mayonnaise, walnuts and cinnamon in medium bowl with fork. Gently squeeze mixture with fingers to form crumbs; set aside.
Beat remaining 1 cup sugar with eggs in large bowl with wire whisk. Whisk in remaining 1/2 cup Mayonnaise and vanilla. Whisk in remaining 1 cup flour just until combined. Evenly pour into prepared pan, then evenly sprinkle with crumbs.
Bake 20 minutes or until toothpick inserted in centers comes out clean. Cool 5 minutes in pan. Remove coffeecakes to wire rack and cool completely. Sprinkle, if desired, with confectioners sugar before serving.