Preheat the oven to 350° F. Butter two 8-inch round cake pans, line with parchment, then butter again. You can also make this in two 9-inch cake pans — the layers will be slightly thinner.
In a large bowl or the bowl of a stand mixer, whisk together the sugar, flour, cocoa, baking powder, baking soda, and salt. Add the eggs, milk, oil (or butter), and vanilla and mix on medium speed for 2 minutes. Add in the boiling water and mix to incorporate.
Divide the batter into the prepared pans. Bake for 30 to 35 minutes (start checking after 30). The cake is ready when it starts to pull away from the edges and a tester inserted into the middle comes out clean. Let cool for 10 minutes in the pan before turning the cakes out onto a rack to cool.
While the cake bakes, place cream and sugar in a heavy medium saucepan and bring mixture to a boil. Reduce to a simmer and cook for 8 minutes. Remove from heat and add chocolate and butter. Mix well. Blend in a pinch of salt and vanilla. Place in the refrigerator until mixture has cooled and thickened but is not yet firm.
Using a mixer or heavy whisk, beat until the mixture becomes light and fluffy.
To assemble the cake: Place one layer of cake, top down, on a serving plate. If you like fruit and chocolate together, spread the layer with a hefty spoonful or two of raspberry jam. Top with a large dollop of frosting to the first layer. Top with the second layer, top up. Add a thin crumb coat of frosting around the outside of the cake then place in refrigerator to chill and let frosting set, about 15 minutes. Finish frosting cake and decorate however you’d like.