Grease a 2-litre baking dish and heat
oven to 180C/160C fan/gas 4. Boil the
kettle. Put the flours, caster sugar,
cocoa, baking powder, xanthan gum
and a pinch of salt in a large mixing bowl.
Whisk together the coffee, eggs, melted
butter and milk, then pour onto the dry
ingredients and mix together until
smooth. Stir in the chocolate chunks and
scrape everything into the baking dish.
Mix 300ml boiling water from the kettle
with the sugar and cocoa for the sauce,
then pour this all over the pudding batter
– don’t worry if it looks unmixed at this
stage! Bake on the middle shelf of the
oven for 30 mins until the surface looks
firm, risen and crisp. As you scoop
spoonfuls into serving bowls, you should
find a glossy, rich chocolate sauce
underneath the sponge. Eat immediately
with vanilla ice cream or single cream.