1Heat oven to 350°F. Spray 12-cup fluted tube cake pan with cooking spray. In small bowl, mix pecans, granulated sugar and 1 teaspoon of the cinnamon. Sprinkle into pan, turning pan to distribute evenly.
2In large bowl, beat cake mix, brown sugar, 2 teaspoons of the cinnamon, nutmeg, sweet potatoes, oil, yogurt, vanilla and eggs with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Carefully spoon into pan.
3Bake 35 to 40 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes; remove from pan. Cool completely, about 1 hour. Sprinkle lightly with powdered sugar.