Ultimate 9-Layer Smith Island Cake (Rich & Moist!)

IMPORTANT: For accuracy, I would recommend using the gram measurements provided, as those are the exact quantities I use. Cup measurements are given as estimates (based on US cup measurements) to make it easier for those who do not have a scale.

Ingredients

Chocolate Fudge Frosting

▢ 1½ cups (340 g) heavy cream
▢ 2 tbsps (12 g) unsweetened cocoa powder - Dutch processed preferred. Sifted.
▢ 3¾ cups (600 g) semi-sweet chocolate - I use a good quality 50% dark chocolate block
▢ 1½ cups (340 g) unsalted butter - room temperature
▢ ¾ tsp instant coffee powder
▢ ¾ tsp salt - omit if using salted butter
▢ 1 tbsp vanilla extract/essence
▢ 1½ cups (255 g) powdered sugar - also known as icing/confectioners' sugar. Sifted.

Instructions

Chocolate Fudge Frosting

Place the cream into a saucepan over medium heat. Heat until you begin to see small bubbles forming around the edges of the pan. Do not let the cream come to a boil.
Reduce the heat to low and whisk in the cocoa powder until completely smooth.
Add the chocolate, butter, instant coffee powder, salt, vanilla and powdered sugar. Stir gently over low heat until everything has completely melted and the frosting is smooth and silky. Do not allow the mixture to simmer or boil, as this can cause it to split. As soon as everything has melted, remove it from the heat.
Pour the frosting through a fine mesh sieve into a heatproof bowl to remove any small lumps.
Press a piece of plastic wrap directly onto the surface of the frosting to prevent a skin from forming. Leave to cool at room temperature while you prepare the cake layers (see note 1).

Yellow Cake

Preheat oven to 350°F (180°C) conventional (see note 2 if using a convection oven with a fan). Grease the sides of two 8-inch cake pans (I use my homemade cake release) and line the bottoms with parchment paper. If you have additional 8-inch cake pans and a big enough oven, you can prepare those as well to bake more layers at once.
In a medium bowl, sift together the flour, cornstarch, baking soda, baking powder and salt. Whisk until well combined, then set aside.
In a large bowl, cream together the butter, vegetable oil and sugar using a hand mixer or stand mixer for 2 minutes until light and creamy.
Add the whole eggs one at a time, mixing well after each addition. Add the egg yolks and mix until fully incorporated.
Add the vinegar, vanilla and buttermilk, then mix until smooth. The batter may look slightly curdled at this stage, which is completely normal.
Add the dry ingredients to the wet ingredients and gently fold together using a spatula until just combined. Be careful not to overmix.
Measure 1 cup of batter into each prepared cake pan and spread into an even layer. Gently tap the pans on the counter once to remove any large air bubbles.
Bake for 12-13 minutes, or until a toothpick inserted into the centre comes out clean or with a few moist crumbs attached.
Allow the cakes to cool in the pans for a few minutes before running a thin knife around the edges and carefully turning them out onto a wire rack to cool.
Re-grease the cake pans (no need to wash them) and reuse the same parchment paper to bake the remaining cake layers in batches, adding 1 cup of batter to each pan each time. Repeat until all of the batter has been used (see note 3). You should end up with approximately 9 cake layers (8-10 layers is perfectly fine).

Assembly (see video for visual demonstration)

Once the cake layers have completely cooled and the frosting has thickened to a spreadable, slightly runny consistency, you're ready to assemble the cake.
Place the first cake layer onto a serving plate or cake stand and spread a thin, even layer of frosting over the top, taking it right to the edges. An offset spatula works well for creating even layers.
Repeat with the remaining cake layers until all of the layers have been stacked.
Use the remaining frosting to cover the top and sides of the cake. Smooth with an offset spatula or cake scraper if desired. If you have any frosting left over, you can pipe a decorative border around the top of the cake.
Allow the cake to sit for 15 minutes in the refrigerator or 30-60 minutes at room temperature before slicing. This gives the frosting time to set slightly, making the cake easier to slice while allowing the flavours to meld together beautifully. Slice and enjoy!

Notes

Note 1. The frosting should thicken slightly but still be spreadable with a slightly runny consistency when ready to assemble the cake.

Note 2. If using a convection oven (fan bake), bake at 320°F (160°C) as the fan function bakes food faster.

Note 3. If you're short on bench space, transfer the cooled cake layers onto a parchment-lined baking tray as you go, placing a sheet of parchment between each layer as shown in the recipe video. This makes them much easier to store while the remaining layers bake.

Nutritional information are estimates only as they are automatically calculated by a third party application. Actual values may differ based on brands and types of products used.