Preheat your oven to 350°F (175°C). Grease and two nine-inch cake pans. Line the bottom of each pan with a parchment paper round and lightly grease those as well (a light spray of cooking oil works well on the parchment).

In a large mixing bowl, cream together the softened butter and sugar until light and fluffy. Beat in 4 eggs one at a time, then stir in the vanilla extract.

In another bowl, sift together all-purpose flour, cocoa powder, baking soda, and salt.

Gradually blend the dry ingredients into the wet mixture, alternating with 1 ½ cups of water. Mix until just combined.

Pour the batter evenly into the prepared cake pans. Bake for about 30 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cakes to cool in the pans for about 10 minutes, then transfer them to a wire rack to cool completely, removing the parchment paper after you remove them from the pan.

I like to start on this while the cake is cooking so it has time to cool. In a medium saucepan, whisk together the cold whole milk and flour. Heat the mixture over medium heat, whisking constantly until it thickens and has a pudding-like consistency. This should take about 5-7 minutes.

Remove the saucepan from the heat and let the mixture cool completely.

In the bowl of an electric mixer, cream together 1 cup of softened butter and 1 cup of sugar until smooth.

Gradually add the cooled milk-flour mixture and beat on medium-high speed until light and fluffy. Switch to the whisk attachment.

Mix in 1 teaspoon of vanilla extract and whip on high for 7-8 minutes until smooth.

Place 1 cup of chocolate chips in a heat-proof bowl.

In a saucepan, heat 1 cup of heavy cream over medium heat until it bubbles around the edges.

Pour the hot cream over the chocolate chips. Stir until smooth. Add 2 tablespoons of butter and stir until the mixture is shiny and smooth.

Use a serrated knife to trim the tops of the cakes if needed to make them level.

Place one cake layer on a serving platter or cake stand. Spread the filling evenly on top. It will be a very thick layer.

Place the second cake layer on top of the filling.

Pour the warm chocolate ganache over the cake, ensuring it covers the top and sides of the cake. Allow it to set slightly.

Use white icing to pipe small loops or your desired design across the cake (to make it look like that classic ding dong we all picture in our heads).