In a bowl, whisk egg, oil and vanilla together. Set aside.
Stir in the dry ingredients: flax meal, baking powder, cinnamon and sugar-free sweetener.
Stir in the optional ingredients, raspberries and chocolate chips are my favorite.
Transfer into a mug - mine was 2.5 inches in height, that's the minimum required to prevent the muffin from overflowing.
Microwave on high for 1 minute 30 seconds.
Wait 1 minute before eating to not burn yourself.
Sweetener:you can also use stevia drops, adjust to taste usually 1-2 drops are enough. Flavors idea: other delicious flavors are blueberries/lemon zest, walnuts and orange zest, sugar free chocolate chips