Preheat your over on Gas Mark 7/200C for 10 minutes. Whilst this is preheating weigh out all the ingredients.
Place the porridge oats, egg, sweetener and vanilla extract in a bowl. Mix well until all ingredients are properly combined. Now add your blueberries and gently mix these in.
Transfer the mixture to an over proof dish which has good depth as it will rise. (I used a small ceramic one).
Place in the middle of the oven and cook for approximately 25 minutes or until golden and firm to the touch.