Combine the flour, sugar, milk, vinegar, applesauce, baking soda, and vanilla extract together by whisking vigorously, until smooth. Next, beat in the egg. Spray a large cereal bowl with non-stick cooking spray, and pour the smooth batter into the cereal bowl (may fill more than one bowl; just pour into multiple bowls until mix is gone). Baking one bowl at a time, place it in the microwave on high for 2 to 4 minutes, awaiting a toothpick comes out clean. Let cool before serve or frosting!