Chocolate and Nut Layer Cake with Creamy Vanilla and Buttercream: A Decadent Delight

Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
In a medium bowl, sift together the flour, baking powder, baking soda, salt, and cocoa powder.
In a large mixing bowl, whisk together the sugar, eggs, milk, oil, and vanilla extract until smooth.
Gradually add the dry ingredients to the wet mixture, stirring until fully combined.
Slowly pour in the hot water, mixing until the batter is smooth and slightly runny.
Divide the batter evenly between the prepared pans.
Bake for 25-30 minutes, or until a toothpick inserted into the center of the cakes comes out clean. Let the cakes cool in the pans for 10 minutes before transferring to a wire rack to cool completely.
Make the Creamy Vanilla Filling:

In a medium saucepan, combine the heavy cream, milk, sugar, and cornstarch.
Cook over medium heat, whisking constantly, until the mixture thickens (about 5-7 minutes).
Once thickened, remove from heat and stir in the vanilla extract. Let it cool to room temperature, then refrigerate to fully set.
Make the Buttercream Frosting:

In a large mixing bowl, beat the softened butter on medium speed for 2-3 minutes until creamy and smooth.
Gradually add the powdered sugar, one cup at a time, beating well after each addition.
Add the vanilla extract and a pinch of salt, then beat in the heavy cream (1 tablespoon at a time) until you reach your desired frosting consistency.
Assemble the Cake:

Once the cake layers are completely cooled, slice each layer in half horizontally to create four layers.
Place the first layer of cake on a serving plate or cake stand.
Spread a layer of creamy vanilla filling on top of the cake, followed by a sprinkle of chopped nuts.
Repeat this process with the remaining layers, stacking them one by one.
Once all layers are stacked, apply a crumb coat of buttercream frosting (a thin layer to seal in the crumbs). Refrigerate the cake for 30 minutes to set.
Frost the Cake:

After the crumb coat has set, generously frost the top and sides of the cake with the buttercream frosting.
Garnish the top of the cake with additional chopped nuts for extra flavor and texture.
Serve:

Slice the cake and serve immediately, or refrigerate until ready to serve.
Serving and Storage Tips: