1) Butter and flour a 9-inch spring form pan. Preheat the oven to 350 °F. Butter and flour a 9-inch spring form pan.
2) Sift the all-purpose flour with the baking powder. In an electric mixer, on medium speed, beat the margarine, granulated sugar, vanilla extract and egg yolks until well mixed. With the machine running slowly, add the milk and the sifted flour. Beat for about 4 minutes or until batter is well mixed. Shut down machine and manually mix in the beaten white eggs into the batter.
3) Pour the batter into the prepared pan. BAKE: for about 40 minutes, or until a toothpick inserted in center comes out clean. Cool the cake for 15 minutes. Remove the sides of the pan and cool completely.