Pour the milk and cream in a small stock pot and add the orange and lemon peel, vanilla bean or vanilla paste, and cinnamon stick. Heat over medium-high heat, stirring constantly to prevent scorching, until the milk is just on the bring of boiling. Then turn off the heat, cover (to prevent a skin from forming).Let sit and cool for 30-45 minutes to allow the flavors of the citrus peel, vanilla and cinnamon to infuse the milk. Once cooled down remove the citrus zest, cinnamon stick and vanilla bean (if using).
Towards the end of the cooling process, put the sugar and cornstarch in a mixing bowl along with the egg yolks. Whisk until smooth and pale. Pour some of the milk mixture into the bowl with the egg yolk mixture and whisk together. Next pour all of the egg yolk mixture into the pot with with the milk mixture and whisk until combined. Slowly heat the mixture, whisking constantly, until it is thickened. DO NOT BOIL.Pour the custard into individual ramekins. Cover the ramekins with plastic wrap to prevent a skin from forming on top. Let them cool and then place them in the refrigerator to chill overnight, preferably for 24 hours for best flavor. The longer the custard chills the more time the flavor will have to develop.
Remove the custard from the fridge at least 20 minutes before serving to come to room temperature.Then sprinkle with turbinado sugar. (The more you add, the thicker the crunchy burnt sugar topping will be. But be careful or it will end up being overly sweet.) Use a butane kitchen torch to "burn" the sugar until it's a rich golden brown with some dark areas (see Note for alternate method). The ramekins will be very hot so let them sit for a minute or two and then serve immediately.
Broiler Method: Broiler Method: If you'd rather you can also caramelize the sugar under the broiler in the oven instead of using a kitchen torch. To do this make sure the Catalan Cream is fully set and very cold (straight out of the fridge). Broil until the sugar is caramelized. Note this method runs the risk of cracking the dish so you have to be very careful! Also with broiling it will NOT get as dark and caramelized as with a kitchen torch.