Heat oven to 350°F (325°F for dark or nonstick pan). Spray bottom and sides of 13x9-inch pan with baking spray with flour.
In large bowl, beat cake ingredients with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Pour into pan.
Bake 32 to 36 minutes or until toothpick inserted in center comes out clean. Cool completely, about 1 hour.
In small bowl, mix whipped topping and 1 container yogurt until blended. Serve cake with peaches and topping mixture. Store loosely covered in refrigerator.