Combine milk, lime zest, and canela in a saucepan.

Heat over medium heat until bubbles form around edges (3-5 minutes).

In a separate heatproof bowl, whisk together egg yolks, heavy cream, sugar, cornstarch, and salt.

Ensure no lumps remain in the egg yolk mixture.

Place the bowl on a towel to stabilize it.

Gradually whisk half of the hot milk mixture into the egg-yolk mixture to temper it.

Return the tempered mixture to the saucepan.

Cook, stirring often, until the custard coats the back of a spoon.

Strain the mixture to remove solids.

Chill over an ice bath to cool rapidly.

Place plastic wrap directly on top of the custard to prevent skin formation.

Chill for at least 2 hours.

Sprinkle ground canela on top before serving.