In a large mixing bowl add the butter and cream it with the turbinado sugar.
Stir in the eggs, one at a time, mixing well between each addition.
Stir in the molasses, milk, and mix well. Add the flour and baking powder, cinnamon and ground nutmeg.
Mix until combined and transfer half of the mixture in a well-greased Bundt pan.
Mix the sour cream with the flour and sugar together and add on top of the batter in the pan.
Finally, top the whole Bundt cake pan with the rest of the batter and bake the Bundt cake in an already heated oven at 350 F or 180 C degrees for about 40-45 minutes.
Let it cool slightly, cut slices, and serve with icing sugar on top.