Preheat oven to 350°F (175°C). Grease the cake pan or line it with parchment paper.
In a bowl, whisk flour, baking powder, and salt. Set aside.
Beat butter and sugar until fluffy (~2 mins). Add egg and vanilla, mixing well.
Alternate adding the dry mix and milk to the butter mixture, starting and ending with flour. Mix until just combined.
Pour batter into the pan and bake for 20-25 mins (or until a toothpick comes out clean).
Let cool for 10 mins in the pan, then transfer to a rack. Frost or garnish as desired once fully cooled.
