Heat the hazelnuts in a naked skillet until the skins have loosened. Transfer to a cutting board. When cool enough to handle, roll them with your hands to separate the skins.

Return the hazelnuts to the pan and toast over medium heat. Set aside.

Zest and juice the orange.

In a separate bowl, whisk together the orange zest, flour, baking powder, ground ginger, and salt and set aside.

In a small saucepan over medium heat, melt the butter molasses and 1/2 cup brown sugar. Stir to combine everything well.

Remove from heat and fold in the sour cream.

Preheat the oven to 325 degrees F.  Grease an 8 or 9" springform pan and line the bottom with baking paper. Grease the baking paper as well.

When the liquid sugar mixture has cooled, whisk in the beaten eggs.

Add the dry ingredients in thirds and combine thoroughly.

Transfer the batter to the prepared pan.

Chop the toasted hazelnuts into small pieces and mix with the remaining 2 tablespoons of sugar and nutmeg.

Sprinkle the hazelnut pieces evenly over the top of the batter. 

Bake for 45 minutes or until a knife inserted in the center of the cake comes out clean.

Whisk together the orange juice and powdered sugar.

When the cake comes out of the oven, immediately pour the orange juice/sugar mixture evenly over the top.

Let the cool completely before de-panning. Slice and serve.