Citrus-infused Crema Catalana with Caramelized Sugar

Step 1: In a medium-sized saucepan, combine the milk, cinnamon stick, and lemon or orange zest. Heat the mixture over medium heat until it reaches a gentle simmer. Do not let it boil.

Step 2: While the milk is heating, in a mixing bowl, whisk together the egg yolks, cornstarch, and half of the granulated sugar until the mixture is smooth and well combined.

Step 3: Once the milk is simmering, remove the cinnamon stick and slowly pour the hot milk into the egg yolk mixture, whisking constantly to temper the eggs. This ensures they don't curdle.

Step 4: Pour the mixture back into the saucepan and place it over low heat. Stir continuously with a wooden spoon or spatula until the mixture thickens and coats the back of the spoon. This should take about 8-10 minutes.

Step 5: Remove the saucepan from the heat and stir in the vanilla extract. Allow the mixture to cool slightly.

Step 6: Divide the custard evenly among individual ramekins or shallow heatproof dishes. Cover them with plastic wrap, ensuring the plastic touches the surface of the custard to prevent a skin from forming. Refrigerate the custards for at least 2 hours or overnight to set.

Step 7: Prior to serving, sprinkle each custard with a thin, even layer of Demerara sugar or granulated sugar. Use a kitchen torch to caramelize the sugar until it turns golden brown and forms a crunchy topping. Alternatively, you can place the custards under a broiler for a few minutes until the sugar caramelizes.

Step 8: Allow the crema catalana to cool for a minute or two before serving. It can be enjoyed warm or chilled.

Step 9: Serve the crema catalana as is or garnish it with fresh berries or a sprinkle of ground cinnamon for added flavor and presentation.