To make the Cake: Preheat the oven to 350 degrees F. Grease two 8-inch round cake pans, line the bottoms with rounds of parchment paper, grease the parchment, then flour the insides of the pans, tapping out excess. Set aside.

In the bowl of an electric mixer, add the flour, sugar, baking soda, baking powder and salt. In a medium bowl, mix the melted chocolate, eggs, buttermilk, vegetable oil, water and vanilla.

Add the wet ingredients to the dry ingredients and mix for 2 minutes on medium speed. Scrape the sides and bottom of the bowl and mix for an additional 20 seconds.

Divide the batter evenly among prepared pans. Bake for 20 minutes and rotate the pans in the oven. Continue to bake until a toothpick inserted into the center of one of the cakes comes out almost clean, about 12 more minutes. Cool the cakes (in the pans) on wire racks for about 20 minutes, then carefully turn them out onto cooling racks to cool completely.

Place one of the cake layers on a serving platter or cake stand and spread the dulce de leche over the top in an even layer. Place the other cake layer on top of the dulce de leche upside-down.

To make the ganache: Place the heavy cream and chocolate in a small pot over low heat and stir until you have a smooth consistency. Let it sit for about 10 minutes and pour on top of the cake.