The Best Chocolate Cake

This cake isn't cakey. That probably sounds strange, but I mean that it's not your average birthday cake with layers of buttercream. It's a dense chocolaty flourless cake that isn't a cop out, and is best served with creme anglaise or fresh berries.
It's not just chocolate wither. There's vanilla, espresso, salt, and cinnamon going on there too. You don't taste them all separately, though. All of these additions share flavor notes with the chocolate, and just make the cake taste even more chocolatey. I like to use Valrhona for these because it has a more intense chocolatey flavor than my usual baking favorite, Scharffen Berger, which is sweeter with a little bit more fruit.
If you have a favorite brand, though go ahead and use that. I just prefer the less fruity flavor because the darkness of the Valrhona ties in better with the earthy flavor additions.

Deep Chocolate Cake
10 oz bittersweet chocolate, chopped
1 1/2 sticks unsalted butter, diced
5 large eggs
3/4 cup sugar
1/2 tsp vanilla extract
1/2 tsp instant espresso
1/4 tsp cinnamon
pinch of salt

Preheat the oven to 350ºF. Grease a 9 inch cake pan and dust with cocoa powder, tapping out the extra. In a bowl, beat the eggs with the sugar, and add the vanilla, salt, and cinnamon.
In a small saucepan or microwave safe bowl, melt the butter, and add the espresso powder, then add the chocolate to the hot butter, and stir until melted and smooth.
Slowly drizzle the melted chocolate into the eggs, whisking the whole time.
Pour the batter into the prepared pan and cover with a sheet of tin foil. Put the pan in a roasting pan and fill 1/2 way up the side with boiling water.
Bake the cake for an hour to an hour and15 minutes, or until the cake is set on top. Cool in the pan for 5 minutes before turning out onto a cooling rack and cooling to room temperature.