01 -
Preheat the oven to 350°F. Lightly grease a 9 by 13-inch baking pan and line with parchment paper, leaving enough overhang for easy removal.
02 -
In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
03 -
In a large bowl, beat the unsalted butter and sugar with an electric mixer until light and fluffy, about 3–5 minutes.
04 -
Add eggs one at a time to the butter mixture, beating well after each addition. Mix in the vanilla extract.
05 -
Gradually add the flour mixture and buttermilk to the wet ingredients, alternating between each, beginning and ending with the flour mixture. Mix until just combined.
06 -
Pour the batter into the prepared pan and smooth the surface evenly. Bake for 30–45 minutes or until a toothpick inserted in the center comes out clean. Allow the cake to cool completely.
07 -
In a large bowl or stand mixer fitted with a paddle attachment, beat unsalted butter and confectioner's sugar on low speed, slowly adding heavy cream one tablespoon at a time. Mix until smooth and fluffy. Add vanilla extract and salt, scraping the sides of the bowl to combine thoroughly.
08 -
Once the cake has cooled, apply a crumb coat of buttercream using a silicone spatula to seal in crumbs. Chill the cake for 30 minutes.
09 -
Spread a thick, smooth layer of buttercream over the entire surface and sides of the chilled cake. Use a silicone spatula and cake scraper for an even finish, dampening the spatula slightly if needed.
10 -
Sprinkle green sugar over the buttercream and add drops of red gel food dye for festive decoration. Slice into tree shapes before serving if desired.