Preheat oven to 325ºF. Grease and flour a nonstick bundt pan.
Beat butter and sugar in a standing mixer until light and fluffy, about 3 minutes. Beat in eggs, one at a time, beating about 30 seconds after each. Beat in vanilla.
In a medium bowl, whisk flour with baking soda, salt, and spices. Add one third of flour mixture to butter mixture and beat on low speed till just combined. Add half of the buttermilk and beat again. Repeat with another third of he flour mixture, then the rest of the buttermilk, and finish by beating in the last of the flour.
Gently fold in the apples and scrape batter into prepared bundt pan. Bake about 50 minutes, until cake feels springy when touched and toothpick inserted in centre comes out clean.
Let cake cool for 10 mins in hot pan - this makes the bottom moist and it helps it to release easily from the pan. Wearing oven mitts, flip the cake onto a cooling rack. Knock on the bottom of the pan a few times until you feel the cake release.