Preheat the oven to 350°F (177°C).
Prepare a tube pan or springform pan by buttering and dusting with flour. Set aside.
Whisk all the dry ingredients together in a large mixing bowl.
Add the eggs, butter, and buttermilk to the dry ingredients.
Using an electric handheld mixer, mix all the ingredients together on low for 30 seconds, then increase to high and mix for three minutes. If mixing by hand, use a wooden spoon or spatula and mix thoroughly until all the ingredients are incorporated, and the batter is smooth.
Add apples that have been tossed with a bit of flour to the batter and mix gently to incorporate.
Pour the batter into the prepared pan.
If you want, you can sprinkle the top of the batter with the Turbinado sugar.
Place the pan onto the middle rack of your preheated oven and bake until the top of the cake is golden brown, and a toothpick inserted into the cake comes out clean. The baking time takes approximately 50 minutes.
When the cake is done, remove it from the oven and allow it to cool completely before removing the cake from the pan. Slice, serve, and enjoy!
You can store the cake in the refrigerator, well-wrapped, for 3-4 days. Eat at room temperature or rewarm in 350°F (177°C) oven for 5 minutes. You can also store the cake in the freezer, well-wrapped, for 3 months. Allow the frozen cake to thaw at room temperature and then eat at room temperature or rewarm in a 350°F (177°C) oven for 5 minutes.