*This recipe is gluten-free according to industry standards
whole milk 1 litre
ground cinnamon ½ tsp
caster sugar 80g
caster sugar 250g
Pour the milk into a large pan, add the orange zest and cinnamon, stir well and set over a medium heat. Bring to the boil and simmer steadily until the milk has reduced by 1/3. The easiest way to gauge this is to take a long wooden skewer and put it into the cold milk in the pan. Make a note of the level of the milk by placing your finger at that point, then carefully use a sharp knife to nick a little groove in the stick. Use this mark to test the depth of the milk as it reduces.
To make the caramel, put 250g sugar and 125ml cold water into a heavy pan. Bring to a simmer and stir until the sugar has dissolved. Turn up the heat and boil until you have a deep golden caramel. Pour into a round ceramic or glass ovenproof dish (approx 19cm). Put the dish in a roasting tin.
Once the milk has reduced, heat the oven to 160C/fan 140C/gas 3. Whisk together the eggs and 80g sugar in a mixing bowl until combined but not too aerated. Strain the reduced milk through a fine sieve onto the egg and stir together, trying not to create too many bubbles. Strain the mixture again while pouring carefully into the dish over the caramel. Add enough boiling water to the roasting tin for it to come about halfway up the sides of the dish (you might find this easier to do when the roasting tin and dish are already in place on the oven shelf as it will be quite heavy).
Bake the flan in its water bath for about 30-40 minutes, until just set but with a bit of a wobble in the centre. Remove the flan from the tin and allow to cool at room temperature. Chill in the fridge for at least 6 hours, or preferably overnight.
To serve, slide a table knife around the edge of the dish. Put a large plate over the top and quickly invert to release the flan onto the plate.