Preheat the oven to 180℃
In a small bowl combine the milk, oil, lemon juice and bicarbonate of soda. Set aside
In the ramekin (or another small bowl) combine the cocoa, flour, caster sugar and salt
Pour the wet ingredients into the dry and mix to form a smooth and wet batter.
Either transfer the mix to a ramekin, or if just using a ramekin, clean the edges. Bake for 18-20 minutes until a skewer comes out clean.
Make the icing
Melt together all the ingredients and then pour over the cooled cake. Leave to set. (you can use whatever decorations you like at this point)