Preheat the oven to 180°C (350°F), Gas Mark 4 and grease a 20cm diameter springform tin, then line the base with baking parchment.

Melt the chocolate in a small bowl over a pot of barely simmering water. Remove from the heat and allow to cool.

Mix together the ground almonds, polenta and baking powder in another small bowl.

Beat the sugar and butter in a large mixing bowl until the mixture is light and pale. Add the eggs, one at a time, beating well after each addition. Fold through the melted chocolate until completely incorporated.

Tip the bowl of dry ingredients into this mixture and fold with a spatula until just combined. Add the vanilla extract and fold through.

Pour the mixture into the prepared tin and place it on the middle shelf of the oven to bake for about 40 minutes or until a skewer comes out clean. Remove from the oven and the tin and allow to cool on a wire rack.

Prepare the caramel sauce; place the butter, sugar and golden syrup in a saucepan and bring to a gentle boil until the sugar is dissolved.

Add the cream, vanilla extract and salt and whisk together. Bring to a steady simmer for 3 minutes until the sauce is sticky and thick. (The sauce will keep for up to seven days in a sealed container in the fridge).

Serve the cake warm in slices with a little crème fraîche and a drizzle of caramel sauce.