Black Velvet Cake:

Let 6 tbsp unsalted butter, 3 large eggs, and 3/4 cup of buttermilk come to room temperature.

Place an oven rack in the middle position and preheat your oven to 350 F (175 C). Prep two 9" cake pans by lining the bottoms with parchment paper. No need to grease the sides or the parchment paper. Take 2 cake strips, soak them in cold water for about 5 minutes, shake off excess water but do not wring, and place them around each cake pan.

In a small bowl, add in 1 3/4 cups of cake flour, 1 3/4 tsp of baking powder, 3/4 tsp of baking soda, and 3/4 tsp of salt, and whisk together till they are combined. Set these dry ingredients aside.

Take a large mixing bowl, add in 1/3 cup (2 oz) bittersweet chocolate chips), and microwave for 1 minute in 30 second increments, whisking in between.

To this same large mixing bowl with the melted chocolate, add in 1/2 cup of black cocoa powder, 1/3 cup of hot brewed coffee, 1 tbsp of vanilla extract, and 1/2 cup of vegetable oil. Whisk them together till they are combined. Then slowly mix in the 3/4 cup room temperature buttermilk while whisking, and 2 tsp of white vinegar, and continue to whisk till everything is combined. Set this aside.

In the bowl of your stand mixer, add in the 6 tbsp of room temperature butter, and with a paddle attachment, beat on medium-high speed until the butter is soft, about 2 minutes. While continuing to beat, slowly add in 1 1/4 cups of granulated sugar, and beat for 5 minutes, until it looks fluffy. Then with the beater still on medium-high, add in the 3 large room temperature eggs, 1 egg at a time, waiting till the previous egg is completely combined before adding in the next one.

Turn your stand mixer on to medium-low speed, and alternate between adding the dry ingredients (flour mixture) and the wet ingredients (chocolate mixture), one third at a time, till everything has been added to the stand mixer bowl and the mixture is well combined. Stop the mixer and scrape down the sides and the bottom of the bowl. Then do a final mix on medium speed for about 30 seconds to ensure everything is mixed.

Divide the batter equally between the 2 prepared cake pans, and smooth the top as much as possible.

Bake the cakes in the preheated oven at 350 F (175 C) for 25 to 30 minutes, or until a toothpick inserted in the middle comes out clean. Let the cakes rest on metal racks to cool for about 10 minutes. Then invert the cakes onto the metal racks, left off the pans, and peel off the parchment paper the cakes were baked with. Let the cakes cool completely to room temperature. When they reach room temperature, flip the cakes onto a flat surface (e.g. chopping board) and place them in the freezer for a minimum of 2 hours (these cakes are extremely crumbly, so freezing the 2 layers will help make assembly easier).

Italian Meringue Buttercream Frosting:

Separate 4 eggs into yolks and whites while they are still cold - save the yolks to use for another dish. Let the 4 egg whites come to room temperature. Take 2 cups (4 sticks) of butter and slice them into 1-inch cubes, and let them come to room temperature.

In the bowl of your stand mixer, add in 4 room temperature egg whites and 1/4 tsp of cream of tartar. With the whisk attachment, beat this on medium speed. Slowly add in 1/2 cup of granulated sugar, and continue beating till you see soft peaks forming. Let this rest.

Take a medium sized saucepan and add in 1 cup of granulated sugar and 1/3 cup of water. Heat it over medium-low heat. Wait for the sugar to dissolve completely and the mixture looks clear.

When the sugar has dissolved, attach a candy thermometer and turn up the flame to the highest level possible. Without stirring, continue heating till the sugar-water mixture reaches the softball stage, which is 235 F (110 C). Pay very close attention to the thermometer. If you let the sugar heat pass 235 F, your resulting frosting will be grainy.

As soon as you see the temperature read 235 F (110 C), remove the saucepan from the heat. Turn on the mixer on medium-low speed, and immediately drizzle the hot sugar mixture into the egg-white meringue in a slow steady stream. The sugar should be hot enough to be in the soft-ball stage so it stabilizes the eggs, as well as hot enough to pasteurize the egg whites so they are safe to eat.

When all the hot sugar syrup has been added, continue running the mixer until the mixture cools completely to room temperature, which could take 15 to 20 minutes or so. Do not worry, as you cannot "overmix" this meringue. Letting the mixer run just helps to cool down the meringue faster. It should end up having a nice silky-smooth texture, and it should be the same temperature as the room temperature butter before they are combined.

When the meringue has cooled completely to room temperature (after 15 to 20 minutes of mixing on medium-high, turn the speed down to medium-low. One cube at a time, add in the 2 cups of room temperature butter, waiting for each piece of butter to get incorporated before adding the next one.

If the mixture starts looking curdled, do not worry. It just means the mixture is too cold and it will become smooth once it warms during mixing. Again, buttercream cannot be "over-mixed". If the mixture starts looking soupy, do not panic either. It just means the mixture is too warm (tends to happen when it's a hot day). Just put your bowl in the fridge for 10 - 20 minutes for the mixture to firm up.

Once all the butter has been incorporated, turn the speed back up to medium-high, and add in 1 tbsp of vanilla extract and 1/2 tsp of table salt. Continue mixing the buttercream on medium-high speed for another 5 minutes, or until it's well-incorporated, smooth, and has a silky consistency. Do not worry about over-mixing, as you can't really overmix meringue-based buttercreams.

Transfer 2 cups of the frosting into a small mixing bowl. Add 6 tbsp of black cocoa powder to these 2 cups of buttercream, and mix until it is smooth and well blended. We'll be using this for piping black rosettes at the end.

From the stand mixer with the remaining Italian buttercream,
take 1/4 cup and transfer it to a separate microwavable bowl. Add 2 tsp of orange gel food coloring to this 1/4 cup of buttercream, mix it up a bit, and microwave it for 15 seconds. Microwaving this small portion will allow the colors from the food coloring to take to the buttercream, as food coloring does not readily dissolve into buttercream. Once you have this small portion of buttercream with activated orange coloring, mix it back into the buttercream in the stand mixer to make a big batch of orange buttercream for the cake filling and frosting.

Assembling the Cake:

When the two different colored frostings are ready and the black velvet cake layers have been in the freezer for 2 hours, you're ready to assemble the cake! Place a cake board on a revolving cake stand. Place the first frozen layer of black
velvet cake in the center of the cake board.

Then spread a thin layer of the orange buttercream frosting mixture on top, creating an even and flat layer as much as possible, about 1/4" thick layer of frosting.

Place the second layer of frozen black velvet cake on top, making sure the flatter side is facing up.

Cover the sides of the cake with a thin layer of the orange buttercream frosting, and then the same thing with the top of the cake. This thin crumb coat should catch any crumbs. Place this cake in the fridge for 20 minutes for the crumb coat to firm up. You can store the unused buttercream frosting out at room temperature.

When the crumb coat has hardened, apply a final layer of the orange buttercream frosting around the sides of the cake, as well as the top. Smoothen all the surfaces with an offset spatula as much as possible. And clean off any stray frosting from the base.

Decorating the Cake:

Take some Halloween-themed sprinkles. We're using a combination of black, white, and orange colored Halloween-themed sprinkles. And press them all around the sides of the cake, going about one-third of the way up the sides. Clean off excess from the base.

Place a cat-shaped (or whatever shape you like) cookie cutter in the middle of the cake's top surface. Using a small spoon, sprinkle a thin layer of black sugar into the cutter making sure it goes all the way to the sides and filling in the middle. Smooth out the black sugar with a toothpick, then carefully lift off the cookie cutter, revealing the black cat decoration.

Take the approximately 2 cups of black cocoa frosting that was prepared earlier, attach a large open star tip to your piping bag (I use a #1M tip), and transfer the dark chocolate frosting into the bag.

Create a pattern around the outer circumference of the top surface by making black swirls all around the cake.

Refrigerate overnight for the layers to set, and set it out at room temperature for about 20 minutes before serving to let the Italian buttercream soften a bit. Enjoy!