Add all ingredients except blueberries into an oversized mug. Stir with a whisk and mix until most of lumps are gone and only very tiny Bisquick lumps remain. Drop in blueberries.
Cook in microwave for approximately 1 1/2 -2 minutes. Cake may still have a wet outside, but this is normal. If inside of cake is done (insert a knife to check), then cake is done. Let cake cool in cup before eating.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.