Preheat your oven to 350 degrees, and grease a round 8-inch cake pan generously. Line with parchment paper if desired. Set aside.
In a large bowl, beat together the butter, 1/2 cup sugar, sour cream, vanilla extract, milk, 1 cup flour, baking powder, and salt. The batter will be fairly thick, but don't over mix here. You want the ingredients to be just incorporated and smooth.
In a small bowl, toss the chocolate chunks with the remaining 1 tbs. flour. Fold the entire mixture (including any excess flour) into your batter. Pour the batter into your prepared cake pan. Evenly sprinkle the top with the remaining 2 tbs. sugar.
Bake the cake for 35-40 minutes, or until the top is golden brown, and a cake tester comes out clean. Cool before removing from the pan and slicing to serve. Enjoy!