Place all of the coulis ingredients into a saucepan and bring to the boil. Cook for 10-15 minutes on a medium heat, stirring occasionally, and then turn off the heat and cool completely. It should thicken as it cools.

Next you want to make the ganache so it has time to cool completely before decorating your cake. Break the chocolate into small pieces in a mixing bowl. Add the double cream to a small saucepan and heat until just before boiling. Then pour over the chocolate and stir until melted. Place in the fridge to cool completely for 1-2 hours.

Preheat the oven to 180'C/Gas 4. Grease and line two 20cm round baking tins and set aside while you make the cake batter.

Add the sugar, butter, eggs and buttermilk to a large mixing bowl and beat with an electric whisk for 1-2 minutes. Don't worry if it separates a little - it'll come together in the next step!

Sift in the flour and xanthan gum and beat again until smooth. Pour the cake batter evenly between the two tins. Next take half of the (cooled) coulis and spoon dollops evenly between each tin. Use a knife or skewer to swirl the mixture, then bake in the oven for approx 25-30 minutes. They're ready when a skewer inserted in the centre comes out clean.

Place the cake tins on a cooling rack for approx 10 mins, then turn out the cakes and remove the paper. Let the cakes cool completely on the rack before decorating.

Place one cake on a stand, then spread half the ganache on top, right out to the edges. Spread the remaining coulis on top, then place the second cake on top, gently sandwiching them together. Spread the remaining ganache on top and then decorate with fresh raspberries.