Preheat your oven to 350° F
Grease and line the bottoms of two 8-inch round cake pans with butter
In a heatproof bowl, combine the dark chocolate, diced butter, and hot water. Place the bowl over a pan of simmering water and stir until everything is melted and well combined. Remove from heat and let it cool slightly.
Meanwhile in a large mixing bowl, whisk together the eggs, sour cream, vegetable oil, and vanilla extract until well combined.
Add both granulated sugar and brown sugar to the wet mixture and whisk until smooth.
Pour in the melted chocolate mixture and whisk again until smooth.
Sift the self-raising flour, cocoa powder, baking soda, and salt into the same bowl. Whisk until the mixture is thoroughly combined.
Divide the cake batter evenly between the prepared cake pans and use a palette knife to level the tops.
Bake in the preheated oven for about 35-40 minutes or until a wooden skewer inserted into the center of the cakes comes out clean.
Let the cakes cool in their pans for 10 minutes, then carefully remove them from the pans and place them on a wire rack to cool completely
In a heatproof bowl, combine the dark chocolate chips and diced butter.
In a medium saucepan, heat the double cream until it's just about to boil.
Pour the hot cream over the chocolate and butter in the bowl. Let it sit for 1 minute without stirring, then stir until the mixture is smooth and glossy.
Allow the ganache to cool and thicken before using.
Place one of the cooled cake layers on a cake stand.
Spread approximately 6 tablespoons of the ganache evenly over the top using a palette knife or a spoon.
Carefully place the second cake layer on top, with the flat side facing up.
Cover the top and sides of the cake with the remaining ganache, and roughly smooth the sides.
Decorate the top of the cake with fresh raspberries.