Set your oven to 350°F (175°C) to preheat. Grease a 9-inch cake pan thoroughly with butter or non-stick spray, then sprinkle a light coating of flour inside to keep the cake from sticking. Set the pan aside while you make the batter.

In a large bowl, use an electric mixer on medium speed to beat the softened butter together with the granulated sugar. Continue mixing until the mixture becomes pale, fluffy, and smooth — this usually takes about 3 to 5 minutes and helps create a soft cake texture.

Add the eggs one at a time to the butter mixture, beating well after each addition to combine fully. Then stir in the vanilla extract. Make sure the mixture is smooth and evenly mixed before adding the dry ingredients.

In a separate bowl, sift together the cake flour, baking powder, and salt. Gradually add this flour mixture to the wet ingredients in three parts, alternating with the milk. Begin and end with the flour mixture. Fold gently with a spatula or mix on low speed just until the batter is smooth and free of flour streaks. Avoid overmixing to keep the cake light.

Pour the batter into your prepared pan, smoothing the surface with a spatula. Bake in the oven for 40-45 minutes, or until a toothpick inserted in the center comes out clean. Let the cake rest in the pan for 10 minutes, then transfer it to a wire rack to cool completely.