Fill a 6-quart pot with apples and water. Bring to a boil. Slowly simmer, uncovered, for 40-45 minutes or until the apples are soft. Make a chunky sauce by mashing.
Stir in brown sugar and pie spice; simmer, uncovered, for 10-15 minutes or until liquid is absorbed and sauce thickens. Allow to cool completely.
Preheat the oven to 400°. Cream butter and sugar together until light and fluffy. Add the eggs one at a time, beating well after each addition. Add vanilla extract.
Mix flour, baking powder, and baking soda in another bowl; alternately add flour mixture and buttermilk, beating well after each addition.
Make 8 disks from the dough by dividing it into 8 portions. Cut out eight 9-inch squares. A circle of parchment. Roll out each dough disk with a floured rolling pin.
Place on baking sheets. Bake for 10-12 minutes, or until golden brown. Cool completely on wire racks after removing from pans.
Place one layer on a serving plate; spread with 2/3 cup filling. Continue layering. Place the remaining cake layer on top; wrap tightly in plastic wrap; refrigerate 1-2 days. Sprinkle confectioner's sugar on cake if desired. Enjoy!