The recipe below is enough for 4 sizeable mug cakes. If you wish to make only two you can easily halve it. Make sure not to overfill your mugs and adjust the cooking time if your microwave has a different setting.
Mix the vegetable oil, eggs, yoghurt and half the Nutella together in a bowl.
Sift in the flour, sugar and cocoa powder and mix together until you have a glossy smooth batter.
Add a tablespoon of Nutella in the bottom of 4 mugs (depending on their size you might get 5 servings) and add about 3-4 tablespoons of batter on top. Make sure to only fill the mugs just over halfway up as the cake will rise.
Microwave for 80-90 seconds (my recipe card would not allow me to enter this value!) in a 800W microwave (adjust the cooking time if your microwave has different wattage).
Top with a scoop of vanilla ice cream and a little chocolate sauce and serve immediately.
Whatever mug or ramekin you use for this recipe TAKE CARE not to overfill! The cake will expand in the microwave.