Preheat oven to 350 degrees and line a 2 cupcake pans with paper liners.
In a medium bowl, combine flour, baking powder, and salt. Set aside.
In a stand mixer or in a large bowl and a hand mixer, cream together butter and sugar for about 3-4 minutes, until light yellow and fluffy on medium/medium high speed.
Add eggs, one at a time, mixing well and scraping the sides of the bowl after each addition.
In a small bowl or pourable measuring cup, whisk together sour cream, milk and vanilla. Set aside.
Starting with the dry ingredients, add about 1/3 to the butter mixture and beat until combined.
Add half of the milk/sour cream mixture and mix well. Continue alternating dry and wet ingredients, ending with the dry ingredients.
Pour batter into each cupcake liner filling about 1/2 to 2/3 full. Bake for 16-18 minutes or until a toothpick inserted in the middle of the cupcake comes out clean.
Let cool in the pan for about 10 minutes and then transfer to a wire rack to cool the rest of the way.