In a medium bowl, whisk together flour, baking powder, and salt.
In a large liquid measure cup, whisk together sour cream and milk.
In a large mixing bowl or the bowl of a stand mixer with the paddle attachment, beat butter until creamy. Add the sugar and beat on medium speed until light and fluffy, about 3 minutes.
Add the eggs one at a time, beating until well combined before adding the next. Beat in the vanilla.
Beating on low speed, add a third of the flour, mixing just until combined. Add half of the sour cream mixture, beating just until combined. Continue alternating with the remaining flour and sour cream mixture.
Pour the batter into the pie dish and carefully spread to the edges of the pan.
Bake for 40 to 45 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. You may want to cover with foil after 30 minutes if the cake is already golden brown.
Cool the cake on a wire rack for 15 minutes. Place a cake plate or stand over the top of the cake and carefully invert. Cool for another 20 minutes or completely before serving.