Add in flour, baking powder, and salt, and mix until just combined. Be sure to scrape the sides and bottom of the bowl to make sure everything gets mixed in.
Divide the batter among the three prepared pans. Bake at 350 for 25 to 30 minutes, until a toothpick inserted into the center comes out clean. Let sit in pans for 5 minutes and then transfer to a wire rack to cool completely before layering and frosting with your favorite frosting.
This recipe can be made as three thin 9-inch layers, or two thick 9-inch layers.