1. In a bowl, sift together the flour and xanthan gum.

2. Melt the butter in a saucepan and allow to cool slightly.

3. Mix the eggs, caster sugar and lemon zest into the flour mix.

4. Beat the melted butter into the mixture, mix vigorously, you should have a sticky dough consistency.

5. Add in the almond extract, pistachios and mixed fruit and stir well.

6. Place half of the mix on a baking tray, and flatten down to about 2cm thick. I used damp hands so it doesn't stick to me.

7. Roll the marzipan into a long sausage, so it is just slightly shorter than then the layer of batter mix and lay on top of mixture, press the rest of the mix on top and down the sides to cover the marzipan and join to the bottom layer.

8. Place into a oven preheated to gas mark 4/170c for 40-50 minutes until golden brown. Cool and sift over icing sugar