For starters, I found this on the internet, unfortunately I have no memory of where. I wrote it on paper by hand and then tried it later. It is yummmmmmy.
Nutella Mug Cake
1/4 cup self-rising flour *
1/4 cup sugar (regular white granulated sugar)
3 TBSP cocoa powder
3 TBSP Nutella
3 TBSP milk
3 TBSP oil
Mix all ingredients well in a mug (extra tall mug works best **)
Microwave for 1 1/2 to 3 minutes - in our microwave it works best at 2 minutes, start with 1 1/2 minutes and check it if it is still not done, add 30 seconds at a time until done.
If you want you can add whipped cream on top. We tried it with and with out, personally I like without better.
* To make self-rising flour: for each 1 cup of all-purpose flour add 1/2 TBSP baking powder and 1/2 tsp salt - mix well, keep in a container to use as needed.
** If you only have regular-sized mugs, just place a plate under the mug so you can still eat the parts that overflow. It will look like a volcano of Nutella cake!