Preheat the oven to 350 degrees F (175 degrees C). Grease two 7-inch cake pans and line with parchment paper. Sift self-rising flour into a bowl; add sugar, margarine, and 1/2 teaspoon vanilla extract. Crack in eggs; beat with a wooden spoon or an electric mixer until pale and fluffy, about 3 minutes. Divide batter…