Preheat oven to 325ºF (177ºC). Grease and line two cake pans with parchment paper.
Melt the butter and chocolate together in a bowl, whisk until smooth.
In the bowl of a stand mixer stir the sugar, water and vanilla. Add chocolate mixture to the sugar mixture and mix well.
Add eggs one at a time waiting for each to be mixed in well.
In a separate bowl add the flour, baking soda, baking powder, and salt. Whisk together.
Starting with the dry ingredients, alternate with the addition of the dry mix and the buttermilk.
Split the batter evenly between the two cake pans. Put on a baking tray and place in the oven.
Bake for about 40 minutes or until a toothpick inserted in the middle of the pans comes out clean.
Remove from the oven and cool completely on a cooling rack before removing the cakes from the pans.