In a medium bowl whisk together the buttermilk, eggs, molasses, sugar, vanilla, and ginger. Whisk in the cooled butter, mix well to combine.
In large mixing bowl, whisk together the flour, baking powder, baking soda, salt, ginger, cinnamon, cardamom, nutmeg, and allspice. Pour the wet ingredients into the dry mixture and whisk until just combined and there are no longer any dry streaks of flour.
Pour the batter into an 8" greased and parchment lined pan and bake at 350°F for 45-55 minutes or until a toothpick inserted in the center of the cake comes out clean.
Remove from oven and cool for 10 minutes before turning out onto a rack and cooling completely.
Notes
*if butter solidifies when added to mixture don't worry, it will be blended into small enough pieces that when it bakes it will be fine.