Preheat oven to 350℉/180℃ degrees. Grease a 9-inch pan (round or square). Set aside.
To make the cake:
In a medium bowl sift together flour, baking powder, baking soda and salt. Set aside.
In a mixer bowl fitted with the paddle attachment, beat the butter on medium speed for one minute until creamy. Add sugar and beat on medium speed for about 3-4 minutes, until light and fluffy. Beat in the eggs, one at a time until combined. Scrape down the sides and bottom of the bowl as necessary. Beat in vanilla extract. On low speed, beat in the flour mixture in 3 additions, alternating it with the sour cream in 2 additions (starting and ending with the flour). Do not overmix.