Split the vanilla bean lengthwise and scrape the seeds into a small saucepan. Add the scraped pod, whole milk, heavy cream, lemon zest, and orange zest to the saucepan. Warm gently over medium-low heat until steam rises and small bubbles form at the edge—do not boil. Remove from heat, cover, and let steep for 15–20 minutes to extract flavor.

Prepare egg base

While the milk is steeping, whisk the egg yolks, 1 tablespoon granulated sugar, cornstarch, and a pinch of salt in a medium bowl until mixture is smooth, slightly pale, and sugar begins to dissolve.

Temper eggs

Remove the vanilla pod and citrus peels from the infused milk mixture. Rewarm the milk gently until just warm. Slowly pour about one-third of the hot milk into the egg yolk mixture in a thin stream, whisking constantly to temper the yolks. Continue whisking and gradually pour in another third, then the remaining milk until fully incorporated.

Cook custard

Return the combined mixture to the saucepan and cook over low heat, stirring constantly with a wooden spoon or heatproof spatula. Stir in any residual scraped vanilla pod if desired. Cook until the mixture thickens enough to coat the back of the spoon (about 6–8 minutes); do not boil or it may curdle. When thickened, remove from heat and briefly whisk to ensure smoothness.

Strain and chill

Pour the custard through a fine-mesh sieve into a clean bowl to remove any bits of cooked egg or zest. Divide the custard evenly among six 4–6 ounce shallow ramekins. Let cool to room temperature (about 30 minutes), then cover each ramekin with plastic wrap placed directly on the surface of the custard to prevent a skin. Refrigerate until fully set and chilled, at least 3 hours or up to 2 days.

Finishing / Caramel

Prepare for caramelizing

Remove chilled ramekins from refrigerator about 10 minutes before caramelizing to take the chill off the top slightly—this helps sugar melt evenly.

Caramelize sugar

Evenly sprinkle 1 teaspoon of granulated sugar over the surface of each custard. Using a kitchen torch, hold the flame about 2–3 inches from the sugar and move it in a slow circular motion until sugar melts, bubbles, and forms an amber, glassy crust (10–30 seconds). If you prefer an iron-brand effect and have a preheated metal branding iron, once the sugar has caramelized and cooled for 30–60 seconds, press the heated iron briefly onto the sugar to leave a subtle mark. Alternatively, to caramelize without a torch, place the ramekins under a very hot broiler 3–6 inches from the heat and watch closely until sugar melts and browns—this is faster and requires care to avoid overheating custard.

Cool and serve

Let the caramelized sugar cool and harden for 1–2 minutes before serving so it forms a crisp shell. Garnish each Crema Catalana with an optional small strip of lemon peel twisted on the edge and serve immediately to enjoy the contrast between cold custard and warm brittle caramel.