01 - Preheat oven to 350°F. Grease and flour three 8-inch round cake pans; line bottoms with parchment paper.
02 - Whisk together flour, ground ginger, cinnamon, cloves, nutmeg, allspice, baking powder, baking soda, and salt in a medium bowl.
03 - Beat butter and brown sugar in a large bowl until light and fluffy, approximately 3 minutes.
04 - Mix in molasses until combined. Beat in eggs one at a time, then stir in vanilla extract.
05 - Alternately add flour mixture and buttermilk to wet ingredients, starting and ending with flour mixture. Mix until just combined; avoid overmixing.
06 - Distribute batter evenly among prepared pans and smooth tops. Bake 25 to 30 minutes, until a toothpick inserted in the center comes out clean.
07 - Allow cakes to cool in pans for 10 minutes, then transfer to wire racks to cool completely.
08 - Beat cream cheese and butter until smooth and creamy. Gradually add powdered sugar, vanilla, and salt, beating until fluffy.
09 - Place one cake layer on a serving plate and spread with frosting. Repeat with remaining layers, finishing by frosting the top and sides.
10 - Decorate as desired with crystallized ginger, cinnamon, or festive sprinkles before serving.