Preheat your oven to 350°F. Grease three 6-inch cake pans and line the bottoms with parchment paper.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, cream together the butter and sugar with an electric mixer on high speed until fluffy (about 3-4 minutes).
Add the eggs and vanilla, and mix on medium-high speed until smooth and slightly fluffy (about 2-3 minutes). Scrape the bowl as needed.
Gradually add the flour mixture and buttermilk to the butter mixture, alternating between the two, until everything is combined and smooth. Scrape the bowl as necessary.
Divide the batter evenly among the prepared pans.
Bake for 29-32 minutes, or until a toothpick inserted in the center comes out clean.
Cool the cakes in the pans for 5 minutes, then transfer to a wire rack to cool completely.