Adjust oven rack to middle position and preheat oven to 375°F. Grease and flour (or spray with baking spray) 3 8-inch round cake pans. Set aside.
Combine the flour, baking powder, salt, and baking soda in a medium bowl. Stir with a whisk to combine.
3 cups all-purpose flour, 2 teaspoons baking powder, 1 teaspoon kosher salt, ½ teaspoon baking soda
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar together until smooth, light, and fluffy, about 6-8 minutes.
1 cup unsalted butter, 2 cups granulated sugar
Add the eggs, one at a time, beating just until incorporated after each addition.
4 large eggs
With the mixer set to low speed, add the flour mixture and buttermilk alternately, in 3 additions, beginning and ending with the flour mixture (beat just until each addition is incorporated).
1 cup buttermilk
Stir in the vanilla.
1 teaspoon pure vanilla extract
Divide the batter, equally, between the three cake pans (about 477 grams per pan) and bake for 20-25 minutes, or until a toothpick inserted in the middle of the cakes comes out clean. The cakes should be golden brown, and spring back when lightly pressed in the center.
Transfer the cakes to a cooling rack for 10 minutes then remove the cakes from the pans. Return the cakes to the cooling rack to cool completely.