In a mixing bowl with an electric mixer, combine margarine with sugar and a pinch of salt.
Then add eggs one at a time, vanilla extract, flour with potato starch and yeast and beat until the batter is smooth and creamy.
Grease the cake tin and pour the mixture.
Place into the preheated oven and bake at 350°F for about 40 minutes.
Once cooked, remove from oven and dust with icing sugar.