Preheat the oven to 180°C (350°F) and line a loaf cake pan 20x10x6cm (8x4x3inch) with butter and parchment paper.
To a bowl of an electric mixer fitted with a paddle attachment, add the sugar and room temperature butter. Beat at medium-high speed until creamed, about three minutes.
Add the eggs to the creamed sugar and butter one at a time beating for 1-2 minutes between each addition. Use a rubber spatula to scrape down the sides of the bowl between each addition.
Add the vanilla to the cake mixture, and beat again until combined.
Sift together the flour, baking powder, and salt.
At low speed add the dry ingredients and sour cream to the cake batter by alternating between the two. Starting with the flour mixture and ending with the sour cream. Once added scrape down the sides of the bowl and beat again to make sure everything is well mixed.
In a small bowl combine the chocolate chips and ½ tablespoon of cake flour, fold this through the cake batter using a spatula or wooden spoon.
Pour the batter into a prepared pan and smooth it over with a spatula. Bake for 50 minutes or until a skewer inserted into the center of the cake comes out clean. Remove from the oven.
Allow the cake to cool in its tin for 15 minutes before turning it onto a wire rack to cool completely. Dust with icing sugar, serve, and enjoy!