Preheat oven to 350F degrees.
Grease a 9 or 10-inch springform pan. Place on a rimmed baking sheet (just in case your pan is prone to leaking).
In a medium bowl, whisk together the flour, baking powder, salt, cinnamon, and nutmeg.
In a large bowl of a stand mixer or using an electric hand mixer, cream the butter and sugar together for about 3 minutes until fluffy and light. Beat in the eggs, one at a time. Mix in the vanilla.
Combine the sour cream and buttermilk together in a small bowl or measuring cup.
Turn the mixer to low speed. Alternate between adding the flour mixture and sour cream mixture, beginning and ending with the flour mixture. Don't overmix.
Stir in the apples using a spatula or wooden spoon. Transfer the batter evenly into the prepared pan.
Bake for 40-45 minutes, until the center of the cake is lightly golden and set. A toothpick inserted into the center of the cake should come out clean.
Allow the cake to cool on a wire rack and remove the outer ring of the springform pan. Once cooled, dust generously with powdered sugar. Slice and serve.