This is by far one of the best chocolate truffle cakes I’ve ever had. I’m obsessed with salted desserts at the moment, and even though salted caramel is all the rage I also am a huge fan of sea salt and dark chocolate.
Combine the first 3 ingredients in a large bowl, mix well, then stir in the butter and cocoa powder.
Lightly butter or spray a 9" round spring form pan, then press this mixture firmly into the bottom.
Bake for about 10 minutes, or until lightly browned, then allow to cool while making the filling.
make the filling:
Put the chocolate, butter, brown sugar and cream together in a medium sized heat proof mixing bowl.
Place this bowl over a pot of boiling water, and stir with a spatula until the mixture is melted and combined, remove the bowl and let cool for a few minutes.
Stir in the vanilla and sea salt, then pour this mixture into the spring form pan over the cooled crust, spreading evenly.
Refrigerate uncovered for about 3 hours, then cover with plastic wrap and refrigerate another hour or two - or overnight. Remove from fridge about 30 minutes before serving and sprinkle flaky sea salt over the top.