Warm the milk, sugar, salt, cinnamon sticks, and 1 cup of the heavy cream in a medium saucepan. Once warm, cover, remove from the heat, and let steep at room temperature for 1 hour.
1 cup whole milk, ¾ cup granulated sugar, Pinch of salt, 8 - 10 3-inch cinnamon sticks
Rewarm the cinnamon-infused milk mixture. Remove the cinnamon sticks with a slotted spoon and discard them.
Make the Cinnamon Custard:
Pour the remaining 1 cup heavy cream into an empty large bowl and set a mesh strainer on top. Set aside.
In a separate medium bowl, whisk together the egg yolks. Slowly pour the warm cinnamon cream mixture into the egg yolks, whisking constantly, then scrape the warmed egg yolks back into the saucepan.
5 egg yolks
Stir the mixture constantly over medium heat with a heatproof spatula, scraping the bottom as you stir, until the mixture thickens and coats the spatula (should reach 170 degrees F on an instant-read thermometer). Pour the custard through the strainer and into the cream in the large bowl. Stir until cool over an ice bath.
Chill the Custard:
Chill the mixture thoroughly in the refrigerator, preferably overnight.
Churn the Ice Cream:
Add the custard mixture to your ice cream maker and freeze according to the manufacturer’s directions.