Preheat the oven to 350°F (175°C). Grease two 9-inch round cake pans, line with parchment paper, and dust with flour.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, beat the softened butter and sugar with a mixer on medium-high speed for 4 to 5 minutes, until pale and fluffy.
Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.
Reduce the mixer speed to low and add the dry ingredients in three parts, alternating with the buttermilk. Begin and end with the dry ingredients.
Gently fold in the oil by hand using a spatula until just combined. Do not overmix.
Divide the batter evenly between the prepared pans and smooth the tops.
Bake for 28 to 32 minutes, or until a toothpick inserted in the center comes out clean.
Cool in the pans for 10 minutes, then turn out onto a wire rack to cool completely before frosting.