Add the plain flour, caster sugar, baking powder and salt to a microwave-proof large mug.
Add the milk, oil and vanilla extract to the dry ingredients.
Mix well into a smooth batter.
Add the brown sugar in a layer over the cake batter.
Drizzle the golden syrup over the brown sugar.
Pour the boiling water over everything.
Microwave for 2 minutes.
Leave to cool for a couple of minutes, then serve with your choice of topping. I love it with vegan vanilla ice cream.
