Preheat the oven to 350°F (180°C). Make sure your rack is in the middle position to ensure even baking.

Grease and line two 9-inch round cake pans. You can lightly coat them with cooking spray or butter, followed by a dusting of cocoa powder to prevent sticking. Lining the bottom with parchment paper also makes cake removal much smoother.

In a large mixing bowl, whisk together the all-purpose flour, cocoa powder, baking powder, baking soda, and salt. Make sure everything is evenly distributed. This helps avoid pockets of unincorporated leavening agents in your batter.

Create a well in the center of your dry ingredients. This space will hold your wet ingredients, making the mixing process simpler and more efficient.

In a separate bowl, combine the buttermilk, granulated sugar, vegetable oil, eggs, and vanilla extract. Whisk thoroughly until everything is well blended.

Pour the wet mixture into the well of the dry mixture. Use a hand mixer or stand mixer on low speed if you want a more uniform batter, or simply whisk by hand until you achieve a smooth consistency.

Slowly pour in the hot water (1 cup) while mixing the batter. This is crucial because the hot liquid helps bloom the cocoa powder, intensifying the chocolate flavor.

Continue to stir until no lumps remain, and you have a consistent, liquid-like batter. Don’t be alarmed if it seems runnier than typical cake batters—this is exactly how you want it for a moist, tender crumb.

Evenly divide the cake batter between your two prepared pans.

Tap the pans gently on the counter to release any trapped air bubbles.

Transfer the pans to the preheated oven and bake for about 25–30 minutes, or until a toothpick inserted into the center of each layer comes out clean.

Remove the pans from the oven and place them on a cooling rack. Allow the cakes to cool in the pans for about 10 minutes.

Gently invert the layers onto the rack to cool completely before moving on to the assembly stage. Letting them cool fully ensures that the filling won’t melt or slide off.

In a medium-sized bowl, combine the shredded coconut, sweetened condensed milk, softened butter, and vanilla extract. Mix well until you achieve a thick, uniform consistency.

Taste-test for sweetness and adjust if necessary. You can add a pinch of salt to balance the sweetness if desired.

Chill the mixture in the refrigerator for about 10 minutes. This step makes it easier to spread the filling without it oozing off the cake layers.

Place the first cooled chocolate cake layer on a cake board or serving plate. Use a serrated knife if you need to level the top so it’s flat.

Generously spread half of the coconut filling on top, pushing it outward to the edges to create an even layer.

Place the second cake layer on top of the filling. Press down gently to make sure everything is secure and level.

Spread the remaining coconut filling on top of the second layer if you like that coconut-forward presentation. Alternatively, you can reserve the remaining filling for in-between the layers only and apply a chocolate topping on the outside.

For a quick chocolate ganache: Heat ½ cup of heavy cream in a small saucepan until it’s just simmering. Pour the hot cream over 1 cup of chocolate chips, let it sit for a minute, and then stir until smooth. Allow it to cool slightly before drizzling over the cake.

Sprinkle toasted coconut flakes over the ganache if you’d like a crunchy, toasted garnish.

Refrigerate the cake if your kitchen is particularly warm, or if you prefer a firmer consistency before slicing and serving.