Crema Catalana

Combine the whole milk with the cinnamon stick and lemon zest in a heavy-bottomed saucepan. Set over medium heat and bring slowly to a bare simmer — small bubbles forming at the edge, not a rolling boil. Remove from heat the moment it steams and the first bubbles appear. Cover the pot and let it steep for 20 minutes off the heat. The milk will absorb the fragrant oils from the lemon zest and the warm spice of the cinnamon, building the aromatic base that defines crema catalana from crème brûlée. Strain the milk through a fine sieve to remove the zest and cinnamon, pressing lightly to extract the flavored oils. The milk should smell unmistakably of warm citrus and spice.

In a large bowl, whisk the egg yolks with the caster sugar until the mixture turns pale, thick, and ribbony — lift the whisk and the mixture should fall back in a slow, fat ribbon that holds its shape for 2–3 seconds before dissolving. This takes about 3 minutes of vigorous whisking. Then whisk in the cornstarch until no dry lumps remain. The cornstarch is what differentiates crema catalana from a pure yolk custard — it gives a firmer, slightly starchier set that holds up in the shallow terracotta dishes and allows the crust to be applied without the custard collapsing. Do not skip this step or substitute with flour.

Reheat the strained infused milk over medium heat until it's steaming and just below a simmer. Slowly pour a small ladle of hot milk into the yolk mixture while whisking constantly — this is the temper, which raises the egg temperature gently without scrambling. Pour in a second ladle, then return the entire mixture to the saucepan. Cook over medium-low heat, whisking constantly and making sure to cover every part of the bottom and corners of the pan. The custard will thicken quickly — within 3–4 minutes it will begin to coat the back of a spoon. As soon as it thickens noticeably and the first large bubble pops at the surface, remove from heat. The cornstarch needs to reach just past gelatinization temperature, which happens around the first boil. Pour immediately into shallow terracotta or ramekin dishes. Chill uncovered for at least 3 hours until completely cold and set.

Remove the chilled custard dishes from the refrigerator. Sprinkle an even, thin layer of caster sugar over each custard — about 1 teaspoon per 10 cm dish — and tilt the dish to spread it uniformly to the edges with no bare patches and no thick mounds. The sugar must be dry and even, like a thin sheet of paper. Traditionally crema catalana is finished with a red-hot iron (ferro), but a kitchen torch works perfectly: hold the flame 2–3 cm from the surface and move in tight circles, watching the sugar melt, bubble, and caramelize from the center outward to the edges. Stop the moment the surface turns amber-brown — it continues to darken for a second after the flame moves away. The crema should be served within 10 minutes of caramelizing, before the sugar absorbs moisture and softens.