First add the flour into a mixing bowl. Next add the coco powder and sugar into the mixing bowl, and mix until the dry ingredients have combined.
Now, add the egg and mix until combined. Next add the vegetable oil and mix. Now the milk and the vanilla. And mix until gloppy.
After you have finished mixing add the chocolate chips and mix. Next get your 3 small mugs and pour the batter straight into the mugs about half way up, because this is going to rise.
And Now put the mugs into the microwave for 1 1/2 minutes maybe 2 depends on your microwave.
After you have taken your mugs out of the microwave, let the cool for 3 minutes. After it has cooled sift the icing sugar into a bowl and add the butter into the bowl and mix until creamy. Then add the milk and vanilla and mix.
Now that your Buttercream is ready grab a piping bag and pour your mixture into the piping bag and pip your icing onto your cake and enjoy your less than 5 minutes cake!