Preheat oven to 350°F. Grease and flour a 9-inch Non-stick springform pan.
In a large bowl combine flour, baking powder, baking soda, apple pie spice, and salt.
In another bowl combine, brown sugar, maple syrup, butter, applesauce, buttermilk, and vanilla.
Stir in flour mixture just until combined. Fold in chopped apples.
Spread batter in prepared baking pan.
Prepare the streusel, if using: in a medium bowl combine flour, brown sugar, apple pie spice, and salt. Drizzle melted butter and vanilla. Toss with a fork to combine. Sprinkle the top of the cake with the streusel.
Bake for 25 – 30 minutes, or until a toothpick inserted in center comes out clean. Cool 15 minutes. Remove from pan.