In a medium saucepan combine milk, cream, ground cinnamon, salt, cinnamon sticks, scraped vanilla beans and pods. Heat to simmering, cover, and set aside to steep for 20 minutes.
Once steeped, remove cinnamon sticks and vanilla bean pod. Heat again to barely simmering.
Meanwhile, in a medium bowl whisk together the egg yolks, ½ cup granulated sugar, and cornstarch. Continuously whisking, very slowly pour the hot milk into yolk mixture. Once fully combined, return mixture to saucepan and cook over medium heat. Cook, stirring vigorously until mixture begins to thicken to a pudding-like consistency, and bubbles to break the surface. Immediately pour through a fine sieve and stir in butter. Cover with plastic wrap directly on surface of custard and chill.