Preheat oven to 350°F. Line a 9″x5″ loaf pan with parchment paper, leaving an overhang on 2 sides. Coat with cooking spray.
In a mixing bowl, combine flours, sugar, cocoa powder, baking powder, baking soda and salt. Whisk until combined.
In another bowl, combine sour cream, oil and vanilla extract.
Add the wet ingredients to dry ingredients and mix until combined. Stir in the chocolate chips and hazelnuts. Pour into the prepared pan and bake for 50~60 minutes or until a cake tester inserted into the center of the bread comes out clean.
Cool the bread slightly and pour the glaze while the bread is still warm.