Preheat the oven to Gas Mark 3 / 170°C / 330 °F and line the baking trays with large paper cases.

Using an electric mixer or food processor mix the butter, flour, sugar, cocoa powder, baking powder, and salt together until they form a sandy, crumb-like texture.

In a bowl, whisk the milk and eggs together. With the mixer on a slow speed, gradually pour half of the liquid into the crumb mixture and mix thoroughly until combined and the batter is smooth and thick.

Once all the lumps are gone gradually pour in the remaining liquid and mix until thoroughly combined. Stir in the milk chocolate buttons.

Evenly divide the cake batter between the prepared cases and bake in the oven for twenty to twenty-five minutes.

Remove from the oven and leave to cool slightly before removing them from the tin and placing on a wire rack to cool.

Sift the icing sugar into a large bowl and add the butter, beat together with a wooden spoon or electric mixer. Heat the milk until scalding in a microwave and in a jug, mix in the vanilla and stir until it is all combined and allow to cool.