Beat butter at medium speed of electric mixer. Gradually add sugar; beat well. Add eggs, one at a time, beating after each addition.

Combine flour, baking powder and salt; add to creamed mixture. Stir in apple and vanilla extract. Spoon batter into a greased and floured 13 x 9-inch pan.

Combine sugar and ground cinnamon; sprinkle over cake batter. Bake at 350 degrees F for 45 minutes or until a wooden pick inserted in center comes out clean.
Serve warm or cool.