Mix everything except chocolate chips into an oversized mug until batter is smooth. Sprinkle chocolate chips on top of batter. Cook in the microwave for about 1 minute 40 seconds. Outside of batter may appear wet but the inside should be cooked. Let cake cool a little before frosting.
While cake is cooling, whip the heavy cream and sugar on high speed until peaks form. Put into piping bag and pipe onto cake. Sprinkle with additional mini chocolate chips.
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.