Preheat your oven to 350°F. and prepare THREE 6-inch cake pans by coating generously with vegetable shortening and dust with flour and set aside.
In a large bowl, combine the flour, baking powder, baking soda, and salt and whisk to combine. Set aside.
In the bowl of a stand mixer equipped with a paddle attachment, add the butter and sugar, and mix on high speed until light and fluffy.
Switch to the whisk attachment and add the eggs and vanilla and whisk until fully combined.
Add sour cream and buttermilk and whisk until just combined. Scrape the sides and bottom of the bowl.
Add the dry ingredients into the wet about ½ at a time, fully incorporating after each addition.
Divide the batter evenly between the three pans and bake for 40 to 45 minutes or until a toothpick inserted into the center of the cake comes out clean.
Allow to cool for about 15 minutes in the pan and then flip out onto a wire rack to cool completely.