Preheat oven to 350 degrees. Grease and flour 2, 8" round cake pans.
In a medium bowl, whisk together flour, baking powder, salt and spices. Set aside
In your stand mixer with paddle attachment (or hand blender), cream the butter and sugars on medium high until slightly pale and fluffy, about 3-5 minutes.
Turn speed down to low and add eggs one at a time, mixing well after each addition. Add in molasses and vanilla and blend well.
Alternate adding the flour and the buttermilk, starting and ending with the flour, in 3 additions. Mix just until fully incorporated.
Pour batter evenly into cake pans and bake for 25-30 minutes or until a toothpick inserted comes out clean. Remove and place on cooling rack for 10 minutes, then release from cake pans.
Cakes can be made ahead up to 1 week and stored in the freezer, a half hour before assembling the trifle, remove from freezer to defrost.