Preheat your oven to 350°F (175°C). Grease two 9-inch round cake pans and line with parchment paper.

In a medium bowl, whisk together flour, baking powder, baking soda, salt, ground ginger, ground cinnamon, ground nutmeg, and ground cloves. Set aside.

In a large bowl, cream unsalted butter with granulated sugar and brown sugar until light and fluffy. Add eggs one at a time, then vanilla extract and molasses. Mix until smooth.

With mixer on low, alternately add dry ingredients and buttermilk to the creamed mixture, starting and ending with dry ingredients. Mix until just combined.

Divide the batter between the cake pans, filling about ⅔ full. Bake for 30 to 35 minutes until cakes spring back when touched.

Allow cakes to cool in the pans for about 10 minutes, then transfer to a wire rack to cool completely.

For the buttercream, dissolve coffee powder in milk. Cream butter until smooth, then add powdered sugar and combine. Add coffee mixture and beat until fluffy.

Level the tops of the cooled cake layers if needed. Assemble by spreading buttercream on top of one layer, then stack the second layer and apply a crumb coat of buttercream.

Chill the cake for about 30 minutes. After chilling, apply a thicker layer of buttercream, drizzle with ganache, and decorate with marshmallows and sprinkles.