Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan and dust with flour or line with parchment paper. Measure and sift the flour, then set aside.
In a large mixing bowl, combine sugar and melted butter. Use an electric mixer or whisk to beat until the mixture is smooth and slightly pale, about 2-3 minutes. Look for a creamy texture and uniform color.
Add eggs one at a time to the mixture, beating well after each addition. The batter should become lumpy at first but will incorporate smoothly. Look for a glossy, well-blended mixture.
Pour in vanilla extract and milk, then mix on low speed until just combined. The batter will be liquid but homogeneous, with no streaks.
Gradually add the sifted flour to the wet mixture, folding gently with a spatula or mixing on low speed until smooth and free of lumps. The batter should be pourable but not thin.
Pour the batter into the prepared cake pan, spreading evenly with a spatula. Bake in the preheated oven for 25 minutes, or until the cake is golden brown and a toothpick inserted into the center comes out clean. The edges should slightly pull away from the pan, and you should hear a faint hollow sound when tapped.
