Mix all ingredients into a mug. Make sure you thoroughly scrape 2 tbsp of Nutella into your mug. A lot of times, much of it sticks to the measuring spoon and it can throw off the recipe and make it taste too eggy.
Stir with a small whisk until all ingredients are thoroughly blended in the batter, especially the Nutella.
Microwave for about 1 min 15 seconds. Check on the cake. The top of the cake may look wet and moist but see if the inside section is set and cooked. If it is, you are done. But if you are worried that the wet part might still have raw egg, remove the thin top layer and flip over so that the wet part is sitting inside and no longer facing the top and microwave for about another 20 seconds so that the wet section cooks. Careful not to overcook or else batter gets too dry. Total cook time should be around 1 ½ minutes, and no more than 2.
Wait for the batter to cool before eating, about 10-20 minutes. I don’t recommend eating this straight out of the microwave because it sometimes has a little bit of an eggy taste which goes away if you let the cake cool and set.
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.