Add all of the spices listed, except the ground ginger, into a warm pan. Shake pan to keep spices moving until they become fragrant. Place these spices plus the ginger into a spice grinder and blend until powdery. Set aside.
Preheat oven to 350 degrees.
Butter and sugar a 10" round cake pan. Set aside.
Combine the flour, baking powder, salt, baking soda and spices then sift to mix. Set aside.
In a small bowl, add the chocolate and then pour over the hot coffee. Allow to sit for about a minute then whisk to combine. Chocolate should be runny at this point.
In the bowl of your stand mixer, beat the 2 eggs until foamy and lighter in color. Add sugar and whip to combine. Add the buttermilk and vanilla and mix just to combine. Add the chocolate and coffee mixture and blend on medium for about a minute, scraping sides as needed. Add the flour and spice mixture and blend on medium until fully combined, scraping sides as needed. Fold in the 1/2 cup of chocolate pieces. Pour batter into prepared pan. Place on middle rack in oven and bake for 45 minutes, or until pick comes out clean. Allow to cool completely before inverting and frosting.
To make buttercream frosting, blend 1 stick (1/2 cup) of softened, unsalted butter and 1 cup of marshmallow fluff until smooth. Add 2 cups of powdered sugar, blend until smooth. Add 1 tsp. vanilla extract and 1 T. finely chopped candied ginger. Combine until thoroughly mixed. Spread onto cooled cake top. Double if looking to cover entire cake.