Start by mixing the sugar with the water and caramelize this on a medium high heat. Stir it as little as possible to prevent it from crystalizing.
When you’re happy with the color while stirring add the cream. Also add the milk and the cinnamon stick.
Then transfer the egg yolk into a bowl and while stirring slowly add the hot caramel liquid.
Now pour it back into the pan and while stirring heat it up till the temperature is 85 °C.
Then pour it into a bowl, cover it and let it infuse in your fridge. I left my base overnight.
The next day you can remove the cinnamon stick and add the mascarpone, the orange juice, the zest from half an orange and the zest from half a lemon. Now use a hand blender to blend it till smooth.
If you want you can also use other or more spices and citruses, but this combo is a Catalana classic. Yuzu and vanilla would be great as well!
Then pass it through a fine sieve. After that transfer it into a siphon and charge it with one charge.
You can keep it in your fridge for three days and use the espuma straight from the fridge. This would be delicious with an almond crumble, citrus segments and a white chocolate pastry cream.