Spanish
Heat the milk with the lemon peel and cinnamon stick until it just starts to steam, then take it off the heat and leave to infuse for 15 minutes; remove the peel and cinnamon.
Cook 120 g of sugar with 30 ml of water in a small pan over medium heat, without stirring, until it turns a deep amber caramel, 6-8 minutes.
Pour the caramel straight into a 20 cm round mold or 8 individual ramekins and tilt to coat the base; let it set.
Heat the oven to 160C and bring a kettle of water to a boil.
Whisk the eggs with 100 g of sugar until just combined, pour in the warm milk while whisking, and strain the mixture over the caramel.
Set the mold in a deep roasting pan, pour hot water into the pan to halfway up the sides and bake for 45-50 minutes (25-30 minutes for ramekins) until the custard is set but still wobbles slightly in the center.
Cool, then chill for at least 4 hours; run a knife around the edge and turn the flan out onto a plate so the caramel runs over it.