1 1/2 cups all-purpose flour
1 1/2 teaspoons baking powder
Pinch of salt
1/3 cup best-quality unsweetened cocoa powder
8 tablespoons (1 stick) unsalted butter
1 tablespoon framboise
1/2 cup superfine sugar
1/2 cup light muscovado sugar or light brown sugar
8 ounces best-quality bittersweet chocolate
3/4 cup black coffee and 3/4 cup water, or instant
coffee made with 2 teaspoons instant coffee and
1 1/2 cups boiling water
2 eggs, beaten slightly
8 ounces raspberries plus more, for serving
Confectioners' sugar, for dusting
Preheat oven to 350 degrees F.
Butter an 8-inch springform pan and line the base with baking parchment. Sift the flour, baking powder, salt, and cocoa powder together in a bowl and set aside. Put the butter, framboise, sugars, chocolate and coffee with water in a heavy-bottomed saucepan and stir over low heat until everything melts and is thickly, glossily smooth.
Stir this mixture into the sifted flour and cocoa. Beat well until all is smooth and glossy again, then beat in the eggs. This will be runny - don't panic, and don't add more flour; the chocolate itself sets as it cooks and then cools.
Pour into the prepared pan until you have covered the base with about an inch of the mixture, and then cover with raspberries and pour the rest of the mixture on top. You may have to push some of the raspberries back under the cake batter by hand. Bake 45 to 50 minutes, until the top is firm and probably slightly cracked; don't try to test by poking in a skewer as you don't want it to come out clean; the grunge is what the cake is about. When it's ready, take the cake out of the oven and put on a rack. Leave in the pan for 15 minutes and then turn out.
When you're just about to eat, dust the cake with the confectioners' sugar tapped through a strainer.
Serve with the additional berries, piled in a bowl.