In a medium saucepan, warm the Whole Milk with the Cinnamon Stick and Lemon Peel over medium heat until it just begins to steam and small bubbles form at the edges; remove from heat and let the flavors steep for 10–15 minutes.
Meanwhile, in a mixing bowl whisk the Egg Yolks with the Granulated Sugar until the mixture is pale and slightly thickened, then whisk in the Cornstarch until perfectly smooth and lump-free.
Strain the infused milk into a measuring cup or bowl to remove the peel and cinnamon, then slowly pour about a cup of the hot milk into the egg mixture while whisking constantly to temper the yolks.
Return the tempered mixture to the saucepan with the remaining milk and cook over low heat, stirring constantly with a wooden spoon or spatula, until the custard thickens enough to coat the back of the spoon (about 4–7 minutes). Do not let it boil.
Remove from heat, strain the custard if desired for extra silkiness, then pour into individual ramekins or a shallow dish. Press plastic wrap onto the surface of the custard to prevent a skin from forming and chill until fully set, at least 2 hours or overnight.
When ready to serve, sprinkle an even, thin layer of granulated sugar over each custard and caramelize with a kitchen torch until the sugar melts and browns to a crisp, amber crust; alternatively place under a very hot broiler for 1–2 minutes, watching closely to avoid burning.
Let the caramelized sugar cool and harden for a minute or two, then serve immediately to enjoy the contrast of cool, creamy custard and warm, brittle topping.
