In a small bowl whisk together the flour, baking powder, and salt. Set aside.
In a medium bowl with an electric mixer, cream the butter and sugar together until light and fluffy.
Beat in the egg until fully incorporated.
Add the sour cream and vanilla. Mix until incorporated.
Add the flour mixture in and stir until combined. Use a spatula to mix in any remaining pockets of flour or butter.
Transfer batter into the prepared pan, smoothing the top. Bake for 20-25 minutes or until the center is set and a toothpick comes out clean.
Allow to cool in the pan for about 10 minutes before transferring to a cooling rack.
Notes
Don't over-mix. Over-mixing your batter can lead to a dry cake texture. To avoid this problem, mix only until all ingredients are just combined.Be easy on the sour cream or yogurt. Although needed for a moist pound cake, too much sour cream or yogurt can produce a dense cake with an unpleasant tangy taste.Bake just until set. Ensure it is fully baked by inserting a wooden toothpick into the cake's center before removing it from the oven. If no batter is sticking to the toothpick when you pull it out, your cake is ready.