Preheat oven to 350F. Butter and flour a 9×5 inch baking tin.

In a medium bowl whisk together the flour, salt, and baking powder then set aside.

In a stand mixer fitted with a whisk attachment cream the butter. Add sugar in and mix until light and fluffy. Scrape the bowl down and beat a few more seconds.

Add the eggs in one at a time while mixing at medium speed. Scrape the bowl down and beat until fully incorporated.

Add the sour cream, and vanilla. Mix until incorporated. Scrape the bowl down.

Add the flour mixture in and mix until combined. Scrape the bowl down and use your spatula to mix in any pockets of flour or butter that remain.

Transfer batter into tin then give a quick smooth to even the batter out a bit. Bake at 350F for about 40 minutes or until the center is set and a skewer comes out clean.

Allow to cool in the tin for about 10 minutes before transferring to a cooling rack.