Pour the milk together with the vanilla extract, cinnamon stick and lemon peel in a pan and bring to the boil.
Turn off the heat and leave for 15 minutes. Then sieve the mixture.
Pour the flavored milk back into the pan and heat until it almost boils.
In the meantime, whisk the eggs with the egg yolks and sugar in a bowl until you have an airy light yellow mass.
Remove the pan from the heat and pour the hot milk with the egg mixture in a thin stream while you continue to beat.
Pour everything back into the pan and let it slowly thicken on low heat. Keep stirring otherwise you get cooked egg and use a wooden spoon to do so. Check if the custard is thick enough by taking the spoon out of the custard en draw a line with your finger. If you can see the line for 2 seconds it thickened enough. Put the heat out immediately.
Strain the custard and divide over the dishes.
Allow to cool for at least 2 hours in the refrigerator.
Put the sugar for the caramel layer in a saucepan and add 100 ml of water.
Bring to a boil over low heat and let it slowly turn into an amber colored caramel (stay there because caramel burns quickly).
Pour the hot caramel over the cold custard, it will harden immediately.
Serve immediately or let it cool in the refrigerator. Tap the caramel when you eat the crema catalana with the back of your spoon to crack it