Preheat oven to 350°F.
Place all ingredients except for the diced apple in a food processor and process until a smooth batter.
Fold in apples. Pour batter into a greased 8x8 baking pan (or 6x8 for thicker bars) and bake for 30-35 minutes or until a toothpick comes up clean.
Allow to cool completely before cutting.
If desired, melt white chocolate chips and drizzle over bars.