Melt 100 grams of good dark chocolate in a double boiler until smooth. Incorporate all the cream to create the ganache.
Put the ganache in a separate bowl and into the freezer. This needs to be fully frozen before the cake can be made.
Take the remaining 250 grams of chocolate and put it into the double boiler. Add all the butter and combine. Reduce the water in the double boiler to a very low simmer, just to keep everything melted.
In another bowl whip the 6 eggs together with the fine brown sugar until there is a layer of foam atop the egg mixture. Stir in the Cointreau
Take the chocolate butter mixture off the double boiler, and set it next to the egg mixture. Add a few spoonfuls of egg mixture to the chocolate stirring somewhat quickly to prevent the eggs from cooking. Once mixed, take the new chocolate-butter-egg mixture and slowly drizzle it into the remaining egg mixture stirring constantly to prevent cooking the eggs.
Add all the flour and stir to incorporate.
Butter your ramekins making sure to get all the way up the sides.
Fill the ramekins about halfway with the cake mixture and in the center drop a ball of frozen ganache in there. I like to use a melon baller as I feel it makes the perfect ratio of cake to frozen ganache.
Preheat the oven to 220 °C and cook the cakes for 12 minutes
Remove from the oven, let rest for 5 minutes, then run a knife around the edge to help release the cakes.
Flip upside down on a clean plate, shake some powdered sugar over the top and garnish with raspberries and blueberries. (You can also add mint if you are so inclined).