1Heat oven to 350°F (325°F for dark or nonstick pan). Grease and lightly flour or spray bottom and sides of 15x10x1-inch pan. In large bowl, stir cake mix, oil, water, vanilla and eggs, using large spoon, until batter forms.
2Set aside 3/4 cup batter; spread remaining batter evenly in pan. Spread pie filling over batter in pan. Drop remaining batter, 1 tablespoonful at a time, onto pie filling, spreading slightly.
3Bake 32 to 36 minutes or until toothpick inserted near center of cake comes out clean. In microwavable bowl, microwave frosting uncovered on High 20 to 30 seconds or until melted; stir. Drizzle over warm coffee cake. Cool 30 minutes. Serve warm or cool. Store loosely covered.