Preheat oven to 160 degrees C. Grease and line two 22cm round cake tins.
Sift flour, sugar, cocoa, baking powder and a pinch of salt into a bowl of an electric mixer.
Add milk, oil, eggs and vanilla; mix on medium speed until combined. Combine boiling water and coffee; add slowly to mixture (on slow speed). Increase speed; beat until smooth.
Divide mixture between tins. Bake for 40-45 minutes, until skewer inserted in centre comes out clean.
Allow to cool for 10 minutes; turn out on wire rack.
When completely cool, make the buttercream and use to sandwich cakes and cover top.