Pre-heat the oven to 350F (175C) and lightly grease/flour a 9-inch round cake mold.
Sift the flour in a medium sized mixing bowl.
Use a mixing spoon to stir in the sugar and cocoa powder.
Mix in the salt and baking soda.
Make three holes: a large one for the melted butter or oil, and two smaller ones for the vinegar and the vanilla.
Add the water and continue mixing with the spoon until you have a smooth batter.
Pour the cake batter into the baking mold and bake at 350 for ~30 minutes or until you stick a toothpick in the middle and it comes out clean.
Remove the cake from the oven and let it cool down.
To prepare the chocolate ganache frosting, melt the butter in small saucepan over very low heat. Once the butter is melted add the chocolate, cut into chunks, and continue cooking at a low/simmer heat level. Stir occasionally and once all the chocolate is melted, stir in the cream and mix well. Remove the chocolate frosting from the heat and let it cool down a bit before using.
Gently remove the cake from the pan –or you can also just leave the cake in the pan and add the frosting on top if you prefer.
Use a spatula to spread the chocolate frosting on top of the cake and on the sides (if removed from the cake mold). Add any additional toppings, then let the frosting set and solidify a bit before cutting and serving the cake. If you refrigerate the cake, let it sit at room temperature for at least 30 minutes before serving so that the frosting can soften up.
Notes
This recipe will yield a small round (9 inch) cake, for a larger cake (9x13) or 2 smaller ones, just double the quantities listed below (for the larger pan the baking time will be closer to 45 minutes) .