Step 1

Preheat oven to 180C. Grease an 8-cup capacity bundt tin with melted butter and dust with flour, shaking off the excess. Refrigerate while you prepare the batter to allow the butter to harden.

Step 2

In the bowl of a stand mixer, or using hand-held beaters, cream butter and sugar until pale. Add eggs one at a time, beating well between each addition. Beat in espresso. Add sour cream and flour and beat until well combined. Remove half the mixture to a bowl. Add cocoa to the remainder and beat to combine.

Step 3

Dollop a spoonful of coffee batter into the tin. Dollop a spoonful of chocolate batter on top. Continue adding spoonfuls of batter, alternating, until you have used it all. Gently shake the tin to settle the batter and smooth the top. Bake for 40-50 minutes until a skewer inserted into the centre comes out clean.

Step 4

Allow to cool slightly in the tin, then turn out onto a cake rack to cool completely.

Step 5

To make icing, sift icing sugar and cocoa into a bowl. Add butter and enough espresso to form a smooth, spreadable consistency. Drizzle over cooled cake.