Preheat oven to 350°. Spray 3 (9-inch) round cake pans with baking spray with flour.
In a large bowl, beat butter and sugar with a mixer at medium speed until fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well after each addition.
In a medium bowl, whisk together flour, baking powder, cinnamon, baking soda, nutmeg, salt, ginger, cloves, and allspice. In a small bowl, whisk together buttermilk and vanilla. With mixer on low speed, gradually add flour mixture to butter mixture alternately with buttermilk mixture, beginning and ending with flour mixture, beating just until combined after each addition. Divide batter among prepared pans.
Bake until a wooden pick inserted in center comes out clean, about 25 minutes. Let cool in pans for 10 minutes. Remove from pans, and let cool completely on wire racks. Spread Molasses Buttercream between layers and on top and sides of cake. Drizzle with molasses, if desired. Store in an airtight container for up to 3 days.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/buttermilk-spice-cake-with-molasses-buttercream-recipe/