Place chopped chocolate in a large heatproof bowl.
In a medium saucepan, combine heavy whipping cream and butter. Cook over med heat, stirring often, until it just starts to simmer.
Pour hot cream over chopped chocolate and cover bowl with plastic wrap. Let sit 5 minutes.
Stir gently with a spatula until completely smooth.
Place plastic wrap directly on top of chocolate ganache. Allow to thicken and set overnight.*
Chocolate Gingerbread Cake:
Preheat oven to 350F, grease three 6" round baking pans and dust with cocoa powder. Line bottoms with parchment.
Place all dry ingredients into the bowl of a stand mixer fitted with a paddle attachment. Stir to combine.
In a medium bowl whisk all wet ingredients (pour water in slowly as not to cook the eggs if very hot).
Add wet ingredients to dry and mix on medium for 2-3 mins. Batter will be very thin.
Pour evenly into prepared pans. I used a kitchen scale to ensure the batter is evenly distributed.
Bake until a cake tester comes out mostly clean. A total of 30-35mins.
Cool 10 minutes in the pans then turn out onto a wire rack to cool completely.
Cut each layer of cake in half horizontally.
Place one layer of cake on a cake stand or serving dish. Top with about 1/2 cup ganache. Repeat with remaining layers. Frost and smooth the outside with a thin crumb coat. Chill for at least 20mins until firm and set.**
Frost the chilled cake with the remaining ganache. It will start to set against the cold cake.
Use a decorating comb (I used the bottom side of the one here) on the sides and top of the cake. Run it across the cake a few times to create a rustic look.
Decorate the top with thyme sprigs and pomegranate seeds if desired.
* You can speed up the thickening of the ganache by placing the it in the fridge, but you need to stir it often. ** If the ganache is too thin or soft and the cake layers start to slide around a bit during assembly, you can place 3-4 bamboo skewers into the top of the cake as support. You'll need to trim the skewers to the proper height of the cake.