Heat oven to 350°F. Spray 13x9-inch pan with cooking spray. In small bowl, mix streusel ingredients with fork until crumbly; set aside.
In large bowl, beat sugar, yogurt, oil, vanilla and eggs with electric mixer on low speed about 30 seconds or until blended. Add all remaining ingredients except apples; beat on low speed about 1 minute or until blended. Stir in apples. Spread batter in pan. Sprinkle evenly with topping.
Bake 40 to 45 minutes or until toothpick inserted in center comes out clean. Serve with ice cream or whipped cream, if desired.