Step 1In a medium saucepan, heat the milk over medium heat with the cinnamon and lemon zest until it starts to simmer. Remove from the heat and set the pan aside to infuse for 30 minutes.
Step 2Mix the cornstarch and half-cup sugar in a separate bowl. Set aside.
Step 3In a medium bowl, whisk the egg yolks.
Step 4Return the saucepan to the stove top and, over medium heat, bring the milk mixture back to a simmer. When the milk is hot, add it little by little to the egg yolks, then return the mixture to the heat, and stir in the sugar blend.
Step 5Place on medium heat until the mixture is thickened, about 3 minutes.
Step 6Remove the zest and cinnamon, and pour the mixture into cazuelas or small gratin dishes, about two-thirds cup per portion. Chill thoroughly until set.
Step 7When ready to serve, sprinkle 1 1/2 teaspoons of sugar in an even layer over the crema and torch until burnt, or place the cazuelas on a sheet tray under the broiler until the sugar starts to turn dark brown, about 8 minutes. Let cool before serving.