Preheat oven to 350 degrees F. Grease and flour two 8-inch round cake pans or line bottoms of each pan with parchment paper circles.
In a medium bowl, whisk together the flour, baking powder and salt. Set aside.
In bowl of a stand mixer, cream the butter and sugar together until light and fluffy, about 2-3 minutes, scraping down the sides of the bowl a couple of times during mixing.
Add the eggs to the butter and sugar, one at a time, beating well after each addition, then mix in the vanilla.
Add the flour mixture and the milk alternately, about ⅓ of each at a time, mixing between additions just until combined.
Divide the batter evenly between the two prepared round pans, then bake for 30-35 minutes, until a toothpick inserted into the center of each cake comes out clean. If using larger 9-inch pans, the cakes will be a little thinner and bake in slight less time (around 23-27 minutes), and if making cupcakes, they will bake for 18-21 minutes.
Remove the cakes from the oven and cool for 10 minutes before running a sharp knife around the edges, then gently turning the cakes out onto a wire cooling rack to cool completely.
Trim the tops of the completely cooled cakes so they are level, then frost with chocolate buttercream and decorate with sprinkles.