Preheat oven to 350°F. Grease two 8 or 9-inch cake pans and line with parchment paper, then grease the parchment paper.
MAKE THE CAKE
Add flour, sugar, cocoa, baking powder, baking soda, and salt to the bowl of your stand mixer.
Add the wet ingredients (sour cream, vegetable oil, eggs, vanilla, and hot coffee) to the dry ingredients. Mix on medium speed until well combined, about 2 minutes.
Stop the mixer and scrape the sides and bottom. Mix again until combined about 20 to 30 seconds. Don't over mix.
Divide them equally between your cake pans.
Bake for 23-26 minutes or until a toothpick inserted in the center comes out clean. Baking times vary, so keep an eye on it. The cakes are done when a toothpick inserted in the center comes out clean. Even when they're done, the center may sink slightly.
Cool the cake completely in the pans on a wire rack.
MAKE THE BUTTERCREAM
Using a stand mixer fitted with a paddle attachment beat the butter on medium speed until creamy and smooth, about 2 minutes. Add confectioners’ sugar, cocoa powder, 3 Tablespoons heavy cream, salt, and vanilla extract. Beat on low speed for 30 seconds or until creamy and smooth.
FROST THE CAKE
If the cake layers are domed on top, use a large serrated knife to slice a thin layer off the tops to create a flat surface.
Place 1 cake layer on your cake stand. Evenly cover the top with frosting. Top with 2nd layer and spread remaining frosting all over the top and sides. Repeat if you have another layer.
Refrigerate the cake for at least an hour before slicing it. This helps the cake hold its shape when cutting.
Store in an airtight container in the refrigerator for up to 5 days.
MAKE THE TREES
Notes
Add ¼ cup more confectioners’ sugar or cocoa powder if frosting is too thin or more cream if it's too thick.