Make a corn starch slurry by mixing 2 tablespoons of corn starch with 2 tablespoons of water.
In a saucepan, combine the 5 egg yolks and ½ cup of sugar. Whisk until well combined.
Add the corn starch slurry, 2 ½ cups of whole milk, the orange peels, and 1-2 cinnamon sticks to the saucepan.
Cook the mixture over medium heat, stirring constantly, until it thickens to a custard-like consistency.
Remove the orange peels and cinnamon sticks.
Serve the custard warm or chilled, and top with orange zest.
