Add dry ingredients to a coffee mug and mix well with a fork.
Add the egg and mix thoroughly.
Pour in the milk, oil, and vanilla and mix well, being sure to scrape the edges of the cup to incorporate all the dry ingredients.
Add the chocolate chips and mix again.
Place the mug in the microwave and cook for 3 minutes on high.
The cake will rise over the top of the mug and then sink down when the microwave is turned off. Allow to cool a little, then tip out onto a plate. Run a knife around the edge if it doesn’t slide out easily. Serve with coconut yoghurt or ice cream.