Preheat oven to 180°C (160°C fan-forced). Lightly grease and line the base and side of a deep 20cm round cake pan with non-stick baking paper.

Sift flour, cocoa, baking powder and bicarbonate of soda into a large bowl. Add sugars and salt; whisk to combine.

Combine eggs, oil, sour cream and vanilla in a separate bowl; whisk to combine. Whisk into flour mixture until a thick batter then gradually whisk in hot water until batter is smooth and well combined.

Pour into prepared tin. Bake for about 50 minutes or until a skewer comes out clean. Set aside to cool in tin for 15 minutes. Turn out onto a wire rack to cool completely.

To make the chocolate cream cheese frosting, place the butter and cream cheese in an electric mixer and beat for about 3 minutes or until smooth and creamy.

Scrape down the sides of the bowl, then add the icing sugar and cocoa and beat for a further 3 minutes or until pale and fluffy. Set aside.

Trim the top off the cooled cake if needed. Halve the cake horizontally. Place one cake base on a cardboard cake board or cake stand. Spread with 1 ¼ cups of frosting and sandwich with remaining cake. Spread icing over the top and sides of cake. Refrigerate for 30 minutes, for icing to set.

To decorate, press the chocolate chips on the side of the cake. Top the cake with the remaining chocolate chips. Refrigerate until ready to serve.