Preheat the oven to 350° and position a rack in the lower third. Butter and flour a 12-cup bundt pan. Sift the cake flour, cinnamon, nutmeg, mace, salt and baking soda onto a sheet of wax paper. In a large bowl, using an electric mixer, beat the remaining 3 sticks of butter until creamy. Add the remaining 2 cups of granulated sugar and the vanilla and beat at medium-high speed until light and fluffy, about 5 minutes. Add the eggs, 1 at a time, beating well between additions. Add the dry ingredients in 3 batches, alternating with the sour cream; beat just until combined. Stir 1/2 cup of the batter into the apples, then stir the apple mixture into the remaining batter.