Add the Milk (3 tablespoon), Egg (1), Vegetable Oil (2 tablespoon) and Nutella® (3 tablespoon) to a high measuring cup.
Whisk well. Then add the Brown Sugar (3 tablespoon) and a pinch of Salt (to taste).
Whisk well again. Then add the sifted the Self-Rising Flour (4 tablespoon).
Whisk the chocolate batter well. Then divide it over 2 large microwave resistant mugs or ramekins.
Place one in the Panasonic Microwave Oven and turn it on high. Let the mug cake cook for 2 minutes. The batter should have set. If not, cook it for 20 seconds more. Then remove the mug and cook the other one in the microwave. Serve warm and enjoy! Cooking results may vary depending on microwave oven used.