1. Preheat oven to 350F. Lightly grease a 10-12 oz ramekin or similar round baking dish.
2. In a small mixing bowl, add all 4 ingredients. Mix with a whisk until batter is smooth and egg is completely beaten into the batter. Pour batter into baking dish.
3. Cook for 18-20 minutes, until top of the cake is just cooked. When you touch the surface of the cake, it should gently bounce back rather than stay sunken in. Let cake cool for a few minutes before eating. I recommend that you top with ice cream, or some kind of syrup as the cake is a little plain on its own.