Preheat oven to 350 F. Line a 9”x3” loaf pan with parchment paper and grease the exposed parts.
Sift flour, baking powder and baking soda in a large bowl and mix to blend. Mix in chocolate chips, and chopped hazelnuts.
In a large bowl, mix the sugars, vegetable oil, sour cream, and eggs and whisk until smooth. Set the bowl aside for about 10-15 minutes.
Mix the dry mixture over the wet mixture and mix just until the flour is hydrated. Lumps are ok.
Transfer the batter into the greased pan and bake over the medium oven rack for 45-50 minutes. Or until the bread is puffy, golden brown and a tooth pick comes out of the center with a few moist crumbs.
Remove from the pan and allow it to cool for 15-20 minutes before inverting and serving.
When ready to serve mix the powdered sugar with the cinnamon, mix in the milk until smooth. Drizzle over the bread and serve.