1 2/3 cups (200 grams) flour
1/2 teaspoon baking soda
scant half cup (50 grams) cocoa powder
hefty pinch salt
1/3 cup (80 grams) heavy cream
1 cup (175 grams) roughly chopped chocolate, plus additional handfuls set aside if you'd like a chunky cake (optional)
1 1/2 sticks butter, softened to room temperature
1 1/4 cups sugar (275 grams)
half a cup (125 grams) boiling water
1/2 cup water
2 teaspoons cocoa powder
scant 1/2 cup (100 grams) sugar
Preheat your oven to 350° Fahrenheit. Butter a loaf pan, and line it with parchment paper (seriously, you need both fronts — this cake is a sticker).
Sift together the flour, baking soda, cocoa powder and salt, and set aside.
In a small saucepan, heat the cream until it's steamy and thinking about simmering. Turn off the heat, and toss the chopped chocolate in the bowl. Let sit for a minute or two to soften the chocolate, then stir until smooth. Let cool slightly.
In a large mixing bowl, beat the butter and sugar together (it doesn't have to be super fluffy). Add the eggs, stir to combine, then add the chocolate mixture. Stir in the flour/cocoa powder, then the boiling water (carefully, of course!). If you're using the reserved chocolate chunks, fold them in as well, then pour the whole mixture into your prepared loaf pan. Bake until a tester almost comes out clean, ~ 1 hour. Remove and let cool.
As soon as the cake comes out of the oven, stir together the syrup ingredients in a saucepan, and bring to a boil. Reduce the heat until it's just high enough to maintain a simmer, and cook until it thickens slightly, ~5 minutes. Poke a few holes in the cake with a skewer if you like (if your cake didn't crack on its own accord), then pour the syrup over the top. Let cool fully (overnight is fine too), then slice and serve.