Preheat oven to 400 degrees F.
Sift together dry ingredients; flour, baking powder, salt, sugar, ginger, and cardamom. Using pastry blender, cut in the butter to coat pieces with flour. Mixture should look like coarse crumbs. Add in the cacao nibs. Make well in center and pour in heavy cream. Fold everything together; do not overwork.
Press dough out on lightly floured surface into a circle about 8 inches in diameter. Cut circle into 8 wedges. Place scones on ungreased cookie sheet, top with candied ginger, and brush with heavy cream. Bake 15-20 minutes until golden brown.
Let scones cool before drizzling with icing.